feat(cli): MCP server management CLI + OAuth 2.1 PKCE auth

Add hermes mcp add/remove/list/test/configure CLI for managing MCP
server connections interactively. Discovery-first 'add' flow connects,
discovers tools, and lets users select which to enable via curses checklist.

Add OAuth 2.1 PKCE authentication for MCP HTTP servers (RFC 7636).
Supports browser-based and manual (headless) authorization, token
caching with 0600 permissions, automatic refresh. Zero external deps.

Add ${ENV_VAR} interpolation in MCP server config values, resolved
from os.environ + ~/.hermes/.env at load time.

Core OAuth module from PR #2021 by @imnotdev25. CLI and mcp_tool
wiring rewritten against current main. Closes #497, #690.

hermes_cli/main.py

@@ -2958,7 +2958,7 @@ def _coalesce_session_name_args(argv: list) -> list:
     _SUBCOMMANDS = {
         "chat", "model", "gateway", "setup", "whatsapp", "login", "logout",
         "status", "cron", "doctor", "config", "pairing", "skills", "tools",
-        "sessions", "insights", "version", "update", "uninstall",
+        "mcp", "sessions", "insights", "version", "update", "uninstall",
     }
     _SESSION_FLAGS = {"-c", "--continue", "-r", "--resume"}
 
@@ -3702,6 +3702,45 @@ For more help on a command:
             tools_command(args)
 
     tools_parser.set_defaults(func=cmd_tools)
+    # =========================================================================
+    # mcp command — manage MCP server connections
+    # =========================================================================
+    mcp_parser = subparsers.add_parser(
+        "mcp",
+        help="Manage MCP server connections",
+        description=(
+            "Add, remove, list, test, and configure MCP server connections.\n\n"
+            "MCP servers provide additional tools via the Model Context Protocol.\n"
+            "Use 'hermes mcp add' to connect to a new server with interactive\n"
+            "tool discovery. Run 'hermes mcp' with no subcommand to list servers."
+        ),
+    )
+    mcp_sub = mcp_parser.add_subparsers(dest="mcp_action")
+
+    mcp_add_p = mcp_sub.add_parser("add", help="Add an MCP server (discovery-first install)")
+    mcp_add_p.add_argument("name", help="Server name (used as config key)")
+    mcp_add_p.add_argument("--url", help="HTTP/SSE endpoint URL")
+    mcp_add_p.add_argument("--command", help="Stdio command (e.g. npx)")
+    mcp_add_p.add_argument("--args", nargs="*", default=[], help="Arguments for stdio command")
+    mcp_add_p.add_argument("--auth", choices=["oauth", "header"], help="Auth method")
+
+    mcp_rm_p = mcp_sub.add_parser("remove", aliases=["rm"], help="Remove an MCP server")
+    mcp_rm_p.add_argument("name", help="Server name to remove")
+
+    mcp_sub.add_parser("list", aliases=["ls"], help="List configured MCP servers")
+
+    mcp_test_p = mcp_sub.add_parser("test", help="Test MCP server connection")
+    mcp_test_p.add_argument("name", help="Server name to test")
+
+    mcp_cfg_p = mcp_sub.add_parser("configure", aliases=["config"], help="Toggle tool selection")
+    mcp_cfg_p.add_argument("name", help="Server name to configure")
+
+    def cmd_mcp(args):
+        from hermes_cli.mcp_config import mcp_command
+        mcp_command(args)
+
+    mcp_parser.set_defaults(func=cmd_mcp)
+
     # =========================================================================
     # sessions command
     # =========================================================================

hermes_cli/mcp_config.py

@@ -0,0 +1,635 @@
+"""
+MCP Server Management CLI — ``hermes mcp`` subcommand.
+
+Implements ``hermes mcp add/remove/list/test/configure`` for interactive
+MCP server lifecycle management (issue #690 Phase 2).
+
+Relies on tools/mcp_tool.py for connection/discovery and keeps
+configuration in ~/.hermes/config.yaml under the ``mcp_servers`` key.
+"""
+
+import asyncio
+import getpass
+import logging
+import os
+import re
+import time
+from pathlib import Path
+from typing import Any, Dict, List, Optional, Set, Tuple
+
+from hermes_cli.config import (
+    load_config,
+    save_config,
+    get_env_value,
+    save_env_value,
+    get_hermes_home,
+)
+from hermes_cli.colors import Colors, color
+
+logger = logging.getLogger(__name__)
+
+
+# ─── UI Helpers ───────────────────────────────────────────────────────────────
+
+def _info(text: str):
+    print(color(f"  {text}", Colors.DIM))
+
+def _success(text: str):
+    print(color(f"  ✓ {text}", Colors.GREEN))
+
+def _warning(text: str):
+    print(color(f"  ⚠ {text}", Colors.YELLOW))
+
+def _error(text: str):
+    print(color(f"  ✗ {text}", Colors.RED))
+
+
+def _confirm(question: str, default: bool = True) -> bool:
+    default_str = "Y/n" if default else "y/N"
+    try:
+        val = input(color(f"  {question} [{default_str}]: ", Colors.YELLOW)).strip().lower()
+    except (KeyboardInterrupt, EOFError):
+        print()
+        return default
+    if not val:
+        return default
+    return val in ("y", "yes")
+
+
+def _prompt(question: str, *, password: bool = False, default: str = "") -> str:
+    display = f"  {question}"
+    if default:
+        display += f" [{default}]"
+    display += ": "
+    try:
+        if password:
+            value = getpass.getpass(color(display, Colors.YELLOW))
+        else:
+            value = input(color(display, Colors.YELLOW))
+        return value.strip() or default
+    except (KeyboardInterrupt, EOFError):
+        print()
+        return default
+
+
+# ─── Config Helpers ───────────────────────────────────────────────────────────
+
+def _get_mcp_servers(config: Optional[dict] = None) -> Dict[str, dict]:
+    """Return the ``mcp_servers`` dict from config, or empty dict."""
+    if config is None:
+        config = load_config()
+    servers = config.get("mcp_servers")
+    if not servers or not isinstance(servers, dict):
+        return {}
+    return servers
+
+
+def _save_mcp_server(name: str, server_config: dict):
+    """Add or update a server entry in config.yaml."""
+    config = load_config()
+    config.setdefault("mcp_servers", {})[name] = server_config
+    save_config(config)
+
+
+def _remove_mcp_server(name: str) -> bool:
+    """Remove a server from config.yaml.  Returns True if it existed."""
+    config = load_config()
+    servers = config.get("mcp_servers", {})
+    if name not in servers:
+        return False
+    del servers[name]
+    if not servers:
+        config.pop("mcp_servers", None)
+    save_config(config)
+    return True
+
+
+def _env_key_for_server(name: str) -> str:
+    """Convert server name to an env-var key like ``MCP_MYSERVER_API_KEY``."""
+    return f"MCP_{name.upper().replace('-', '_')}_API_KEY"
+
+
+# ─── Discovery (temporary connect) ───────────────────────────────────────────
+
+def _probe_single_server(
+    name: str, config: dict, connect_timeout: float = 30
+) -> List[Tuple[str, str]]:
+    """Temporarily connect to one MCP server, list its tools, disconnect.
+
+    Returns list of ``(tool_name, description)`` tuples.
+    Raises on connection failure.
+    """
+    from tools.mcp_tool import (
+        _ensure_mcp_loop,
+        _run_on_mcp_loop,
+        _connect_server,
+        _stop_mcp_loop,
+    )
+
+    _ensure_mcp_loop()
+
+    tools_found: List[Tuple[str, str]] = []
+
+    async def _probe():
+        server = await asyncio.wait_for(
+            _connect_server(name, config), timeout=connect_timeout
+        )
+        for t in server._tools:
+            desc = getattr(t, "description", "") or ""
+            # Truncate long descriptions for display
+            if len(desc) > 80:
+                desc = desc[:77] + "..."
+            tools_found.append((t.name, desc))
+        await server.shutdown()
+
+    try:
+        _run_on_mcp_loop(_probe(), timeout=connect_timeout + 10)
+    except BaseException as exc:
+        raise _unwrap_exception_group(exc) from None
+    finally:
+        _stop_mcp_loop()
+
+    return tools_found
+
+
+def _unwrap_exception_group(exc: BaseException) -> Exception:
+    """Extract the root-cause exception from anyio TaskGroup wrappers.
+
+    The MCP SDK uses anyio task groups, which wrap errors in
+    ``BaseExceptionGroup`` / ``ExceptionGroup``.  This makes error
+    messages opaque ("unhandled errors in a TaskGroup").  We unwrap
+    to surface the real cause (e.g. "401 Unauthorized").
+    """
+    while isinstance(exc, BaseExceptionGroup) and exc.exceptions:
+        exc = exc.exceptions[0]
+    # Return a plain Exception so callers can catch normally
+    if isinstance(exc, Exception):
+        return exc
+    return RuntimeError(str(exc))
+
+
+# ─── hermes mcp add ──────────────────────────────────────────────────────────
+
+def cmd_mcp_add(args):
+    """Add a new MCP server with discovery-first tool selection."""
+    name = args.name
+    url = getattr(args, "url", None)
+    command = getattr(args, "command", None)
+    cmd_args = getattr(args, "args", None) or []
+    auth_type = getattr(args, "auth", None)
+
+    # Validate transport
+    if not url and not command:
+        _error("Must specify --url <endpoint> or --command <cmd>")
+        _info("Examples:")
+        _info('  hermes mcp add ink --url "https://mcp.ml.ink/mcp"')
+        _info('  hermes mcp add github --command npx --args @modelcontextprotocol/server-github')
+        return
+
+    # Check if server already exists
+    existing = _get_mcp_servers()
+    if name in existing:
+        if not _confirm(f"Server '{name}' already exists. Overwrite?", default=False):
+            _info("Cancelled.")
+            return
+
+    # Build initial config
+    server_config: Dict[str, Any] = {}
+    if url:
+        server_config["url"] = url
+    else:
+        server_config["command"] = command
+        if cmd_args:
+            server_config["args"] = cmd_args
+
+    # ── Authentication ────────────────────────────────────────────────
+
+    if url and auth_type == "oauth":
+        print()
+        _info(f"Starting OAuth flow for '{name}'...")
+        oauth_ok = False
+        try:
+            from tools.mcp_oauth import build_oauth_auth
+            oauth_auth = build_oauth_auth(name, url)
+            if oauth_auth:
+                server_config["auth"] = "oauth"
+                _success("OAuth configured (tokens will be acquired on first connection)")
+                oauth_ok=True
+            else:
+                _warning("OAuth setup failed — MCP SDK auth module not available")
+        except Exception as exc:
+            _warning(f"OAuth error: {exc}")
+
+        if not oauth_ok:
+            _info("This server may not support OAuth.")
+            if _confirm("Continue without authentication?", default=True):
+                # Don't store auth: oauth — server doesn't support it
+                pass
+            else:
+                _info("Cancelled.")
+                return
+
+    elif url:
+        # Prompt for API key / Bearer token for HTTP servers
+        print()
+        _info(f"Connecting to {url}")
+        needs_auth = _confirm("Does this server require authentication?", default=True)
+        if needs_auth:
+            if auth_type == "header" or not auth_type:
+                env_key = _env_key_for_server(name)
+                existing_key = get_env_value(env_key)
+                if existing_key:
+                    _success(f"{env_key}: already configured")
+                    api_key = existing_key
+                else:
+                    api_key = _prompt("API key / Bearer token", password=True)
+                    if api_key:
+                        save_env_value(env_key, api_key)
+                        _success(f"Saved to ~/.hermes/.env as {env_key}")
+
+                # Set header with env var interpolation
+                if api_key or existing_key:
+                    server_config["headers"] = {
+                        "Authorization": f"Bearer ${{{env_key}}}"
+                    }
+
+    # ── Discovery: connect and list tools ─────────────────────────────
+
+    print()
+    print(color(f"  Connecting to '{name}'...", Colors.CYAN))
+
+    try:
+        tools = _probe_single_server(name, server_config)
+    except Exception as exc:
+        _error(f"Failed to connect: {exc}")
+        if _confirm("Save config anyway (you can test later)?", default=False):
+            server_config["enabled"] = False
+            _save_mcp_server(name, server_config)
+            _success(f"Saved '{name}' to config (disabled)")
+            _info("Fix the issue, then: hermes mcp test " + name)
+        return
+
+    if not tools:
+        _warning("Server connected but reported no tools.")
+        if _confirm("Save config anyway?", default=True):
+            _save_mcp_server(name, server_config)
+            _success(f"Saved '{name}' to config")
+        return
+
+    # ── Tool selection ────────────────────────────────────────────────
+
+    print()
+    _success(f"Connected! Found {len(tools)} tool(s) from '{name}':")
+    print()
+    for tool_name, desc in tools:
+        short = desc[:60] + "..." if len(desc) > 60 else desc
+        print(f"    {color(tool_name, Colors.GREEN):40s} {short}")
+    print()
+
+    # Ask: enable all, select, or cancel
+    try:
+        choice = input(
+            color(f"  Enable all {len(tools)} tools? [Y/n/select]: ", Colors.YELLOW)
+        ).strip().lower()
+    except (KeyboardInterrupt, EOFError):
+        print()
+        _info("Cancelled.")
+        return
+
+    if choice in ("n", "no"):
+        _info("Cancelled — server not saved.")
+        return
+
+    if choice in ("s", "select"):
+        # Interactive tool selection
+        from hermes_cli.curses_ui import curses_checklist
+
+        labels = [f"{t[0]}  —  {t[1]}" for t in tools]
+        pre_selected = set(range(len(tools)))
+
+        chosen = curses_checklist(
+            f"Select tools for '{name}'",
+            labels,
+            pre_selected,
+        )
+
+        if not chosen:
+            _info("No tools selected — server not saved.")
+            return
+
+        chosen_names = [tools[i][0] for i in sorted(chosen)]
+        server_config.setdefault("tools", {})["include"] = chosen_names
+
+        tool_count = len(chosen_names)
+        total = len(tools)
+    else:
+        # Enable all (no filter needed — default behaviour)
+        tool_count = len(tools)
+        total = len(tools)
+
+    # ── Save ──────────────────────────────────────────────────────────
+
+    server_config["enabled"] = True
+    _save_mcp_server(name, server_config)
+
+    print()
+    _success(f"Saved '{name}' to ~/.hermes/config.yaml ({tool_count}/{total} tools enabled)")
+    _info("Start a new session to use these tools.")
+
+
+# ─── hermes mcp remove ───────────────────────────────────────────────────────
+
+def cmd_mcp_remove(args):
+    """Remove an MCP server from config."""
+    name = args.name
+    existing = _get_mcp_servers()
+
+    if name not in existing:
+        _error(f"Server '{name}' not found in config.")
+        servers = list(existing.keys())
+        if servers:
+            _info(f"Available servers: {', '.join(servers)}")
+        return
+
+    if not _confirm(f"Remove server '{name}'?", default=True):
+        _info("Cancelled.")
+        return
+
+    _remove_mcp_server(name)
+    _success(f"Removed '{name}' from config")
+
+    # Clean up OAuth tokens if they exist
+    try:
+        from tools.mcp_oauth import remove_oauth_tokens
+        remove_oauth_tokens(name)
+        _success("Cleaned up OAuth tokens")
+    except Exception:
+        pass
+
+
+# ─── hermes mcp list ──────────────────────────────────────────────────────────
+
+def cmd_mcp_list(args=None):
+    """List all configured MCP servers."""
+    servers = _get_mcp_servers()
+
+    if not servers:
+        print()
+        _info("No MCP servers configured.")
+        print()
+        _info("Add one with:")
+        _info('  hermes mcp add <name> --url <endpoint>')
+        _info('  hermes mcp add <name> --command <cmd> --args <args...>')
+        print()
+        return
+
+    print()
+    print(color("  MCP Servers:", Colors.CYAN + Colors.BOLD))
+    print()
+
+    # Table header
+    print(f"  {'Name':<16} {'Transport':<30} {'Tools':<12} {'Status':<10}")
+    print(f"  {'─' * 16} {'─' * 30} {'─' * 12} {'─' * 10}")
+
+    for name, cfg in servers.items():
+        # Transport info
+        if "url" in cfg:
+            url = cfg["url"]
+            # Truncate long URLs
+            if len(url) > 28:
+                url = url[:25] + "..."
+            transport = url
+        elif "command" in cfg:
+            cmd = cfg["command"]
+            cmd_args = cfg.get("args", [])
+            if isinstance(cmd_args, list) and cmd_args:
+                transport = f"{cmd} {' '.join(str(a) for a in cmd_args[:2])}"
+            else:
+                transport = cmd
+            if len(transport) > 28:
+                transport = transport[:25] + "..."
+        else:
+            transport = "?"
+
+        # Tool count
+        tools_cfg = cfg.get("tools", {})
+        if isinstance(tools_cfg, dict):
+            include = tools_cfg.get("include")
+            exclude = tools_cfg.get("exclude")
+            if include and isinstance(include, list):
+                tools_str = f"{len(include)} selected"
+            elif exclude and isinstance(exclude, list):
+                tools_str = f"-{len(exclude)} excluded"
+            else:
+                tools_str = "all"
+        else:
+            tools_str = "all"
+
+        # Enabled status
+        enabled = cfg.get("enabled", True)
+        if isinstance(enabled, str):
+            enabled = enabled.lower() in ("true", "1", "yes")
+        status = color("✓ enabled", Colors.GREEN) if enabled else color("✗ disabled", Colors.DIM)
+
+        print(f"  {name:<16} {transport:<30} {tools_str:<12} {status}")
+
+    print()
+
+
+# ─── hermes mcp test ──────────────────────────────────────────────────────────
+
+def cmd_mcp_test(args):
+    """Test connection to an MCP server."""
+    name = args.name
+    servers = _get_mcp_servers()
+
+    if name not in servers:
+        _error(f"Server '{name}' not found in config.")
+        available = list(servers.keys())
+        if available:
+            _info(f"Available: {', '.join(available)}")
+        return
+
+    cfg = servers[name]
+    print()
+    print(color(f"  Testing '{name}'...", Colors.CYAN))
+
+    # Show transport info
+    if "url" in cfg:
+        _info(f"Transport: HTTP → {cfg['url']}")
+    else:
+        cmd = cfg.get("command", "?")
+        _info(f"Transport: stdio → {cmd}")
+
+    # Show auth info (masked)
+    auth_type = cfg.get("auth", "")
+    headers = cfg.get("headers", {})
+    if auth_type == "oauth":
+        _info("Auth: OAuth 2.1 PKCE")
+    elif headers:
+        for k, v in headers.items():
+            if isinstance(v, str) and ("key" in k.lower() or "auth" in k.lower()):
+                # Mask the value
+                resolved = _interpolate_value(v)
+                if len(resolved) > 8:
+                    masked = resolved[:4] + "***" + resolved[-4:]
+                else:
+                    masked = "***"
+                print(f"    {k}: {masked}")
+    else:
+        _info("Auth: none")
+
+    # Attempt connection
+    start = time.monotonic()
+    try:
+        tools = _probe_single_server(name, cfg)
+        elapsed_ms = (time.monotonic() - start) * 1000
+    except Exception as exc:
+        elapsed_ms = (time.monotonic() - start) * 1000
+        _error(f"Connection failed ({elapsed_ms:.0f}ms): {exc}")
+        return
+
+    _success(f"Connected ({elapsed_ms:.0f}ms)")
+    _success(f"Tools discovered: {len(tools)}")
+
+    if tools:
+        print()
+        for tool_name, desc in tools:
+            short = desc[:55] + "..." if len(desc) > 55 else desc
+            print(f"    {color(tool_name, Colors.GREEN):36s} {short}")
+    print()
+
+
+def _interpolate_value(value: str) -> str:
+    """Resolve ``${ENV_VAR}`` references in a string."""
+    def _replace(m):
+        return os.getenv(m.group(1), "")
+    return re.sub(r"\$\{(\w+)\}", _replace, value)
+
+
+# ─── hermes mcp configure ────────────────────────────────────────────────────
+
+def cmd_mcp_configure(args):
+    """Reconfigure which tools are enabled for an existing MCP server."""
+    name = args.name
+    servers = _get_mcp_servers()
+
+    if name not in servers:
+        _error(f"Server '{name}' not found in config.")
+        available = list(servers.keys())
+        if available:
+            _info(f"Available: {', '.join(available)}")
+        return
+
+    cfg = servers[name]
+
+    # Discover all available tools
+    print()
+    print(color(f"  Connecting to '{name}' to discover tools...", Colors.CYAN))
+
+    try:
+        all_tools = _probe_single_server(name, cfg)
+    except Exception as exc:
+        _error(f"Failed to connect: {exc}")
+        return
+
+    if not all_tools:
+        _warning("Server reports no tools.")
+        return
+
+    # Determine which are currently enabled
+    tools_cfg = cfg.get("tools", {})
+    if isinstance(tools_cfg, dict):
+        include = tools_cfg.get("include")
+        exclude = tools_cfg.get("exclude")
+    else:
+        include = None
+        exclude = None
+
+    tool_names = [t[0] for t in all_tools]
+
+    if include and isinstance(include, list):
+        include_set = set(include)
+        pre_selected = {
+            i for i, tn in enumerate(tool_names) if tn in include_set
+        }
+    elif exclude and isinstance(exclude, list):
+        exclude_set = set(exclude)
+        pre_selected = {
+            i for i, tn in enumerate(tool_names) if tn not in exclude_set
+        }
+    else:
+        pre_selected = set(range(len(all_tools)))
+
+    currently = len(pre_selected)
+    total = len(all_tools)
+    _info(f"Currently {currently}/{total} tools enabled for '{name}'.")
+    print()
+
+    # Interactive checklist
+    from hermes_cli.curses_ui import curses_checklist
+
+    labels = [f"{t[0]}  —  {t[1]}" for t in all_tools]
+
+    chosen = curses_checklist(
+        f"Select tools for '{name}'",
+        labels,
+        pre_selected,
+    )
+
+    if chosen == pre_selected:
+        _info("No changes made.")
+        return
+
+    # Update config
+    config = load_config()
+    server_entry = config.get("mcp_servers", {}).get(name, {})
+
+    if len(chosen) == total:
+        # All selected → remove include/exclude (register all)
+        server_entry.pop("tools", None)
+    else:
+        chosen_names = [tool_names[i] for i in sorted(chosen)]
+        server_entry.setdefault("tools", {})
+        server_entry["tools"]["include"] = chosen_names
+        server_entry["tools"].pop("exclude", None)
+
+    config.setdefault("mcp_servers", {})[name] = server_entry
+    save_config(config)
+
+    new_count = len(chosen)
+    _success(f"Updated config: {new_count}/{total} tools enabled")
+    _info("Start a new session for changes to take effect.")
+
+
+# ─── Dispatcher ───────────────────────────────────────────────────────────────
+
+def mcp_command(args):
+    """Main dispatcher for ``hermes mcp`` subcommands."""
+    action = getattr(args, "mcp_action", None)
+
+    handlers = {
+        "add": cmd_mcp_add,
+        "remove": cmd_mcp_remove,
+        "rm": cmd_mcp_remove,
+        "list": cmd_mcp_list,
+        "ls": cmd_mcp_list,
+        "test": cmd_mcp_test,
+        "configure": cmd_mcp_configure,
+        "config": cmd_mcp_configure,
+    }
+
+    handler = handlers.get(action)
+    if handler:
+        handler(args)
+    else:
+        # No subcommand — show list
+        cmd_mcp_list()
+        print(color("  Commands:", Colors.CYAN))
+        _info("hermes mcp add <name> --url <endpoint>        Add an MCP server")
+        _info("hermes mcp add <name> --command <cmd>         Add a stdio server")
+        _info("hermes mcp remove <name>                      Remove a server")
+        _info("hermes mcp list                               List servers")
+        _info("hermes mcp test <name>                        Test connection")
+        _info("hermes mcp configure <name>                   Toggle tools")
+        print()

tests/hermes_cli/test_mcp_config.py

@@ -0,0 +1,400 @@
+"""
+Tests for hermes_cli.mcp_config — ``hermes mcp`` subcommands.
+
+These tests mock the MCP server connection layer so they run without
+any actual MCP servers or API keys.
+"""
+
+import argparse
+import json
+import os
+import types
+from pathlib import Path
+from typing import Any, Dict, List
+from unittest.mock import MagicMock, patch, PropertyMock
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(autouse=True)
+def _isolate_config(tmp_path, monkeypatch):
+    """Redirect all config I/O to a temp directory."""
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setattr(
+        "hermes_cli.config.get_hermes_home", lambda: tmp_path
+    )
+    config_path = tmp_path / "config.yaml"
+    env_path = tmp_path / ".env"
+    monkeypatch.setattr(
+        "hermes_cli.config.get_config_path", lambda: config_path
+    )
+    monkeypatch.setattr(
+        "hermes_cli.config.get_env_path", lambda: env_path
+    )
+    return tmp_path
+
+
+def _make_args(**kwargs):
+    """Build a minimal argparse.Namespace."""
+    defaults = {
+        "name": "test-server",
+        "url": None,
+        "command": None,
+        "args": None,
+        "auth": None,
+        "mcp_action": None,
+    }
+    defaults.update(kwargs)
+    return argparse.Namespace(**defaults)
+
+
+def _seed_config(tmp_path: Path, mcp_servers: dict):
+    """Write a config.yaml with the given mcp_servers."""
+    import yaml
+
+    config = {"mcp_servers": mcp_servers, "_config_version": 9}
+    config_path = tmp_path / "config.yaml"
+    with open(config_path, "w") as f:
+        yaml.safe_dump(config, f)
+
+
+class FakeTool:
+    """Mimics an MCP tool object returned by the SDK."""
+
+    def __init__(self, name: str, description: str = ""):
+        self.name = name
+        self.description = description
+
+
+# ---------------------------------------------------------------------------
+# Tests: cmd_mcp_list
+# ---------------------------------------------------------------------------
+
+class TestMcpList:
+    def test_list_empty_config(self, tmp_path, capsys):
+        from hermes_cli.mcp_config import cmd_mcp_list
+
+        cmd_mcp_list()
+        out = capsys.readouterr().out
+        assert "No MCP servers configured" in out
+
+    def test_list_with_servers(self, tmp_path, capsys):
+        _seed_config(tmp_path, {
+            "ink": {
+                "url": "https://mcp.ml.ink/mcp",
+                "enabled": True,
+                "tools": {"include": ["create_service", "get_service"]},
+            },
+            "github": {
+                "command": "npx",
+                "args": ["@mcp/github"],
+                "enabled": False,
+            },
+        })
+        from hermes_cli.mcp_config import cmd_mcp_list
+
+        cmd_mcp_list()
+        out = capsys.readouterr().out
+        assert "ink" in out
+        assert "github" in out
+        assert "2 selected" in out  # ink has 2 in include
+        assert "disabled" in out  # github is disabled
+
+    def test_list_enabled_default_true(self, tmp_path, capsys):
+        """Server without explicit enabled key defaults to enabled."""
+        _seed_config(tmp_path, {
+            "myserver": {"url": "https://example.com/mcp"},
+        })
+        from hermes_cli.mcp_config import cmd_mcp_list
+
+        cmd_mcp_list()
+        out = capsys.readouterr().out
+        assert "myserver" in out
+        assert "enabled" in out
+
+
+# ---------------------------------------------------------------------------
+# Tests: cmd_mcp_remove
+# ---------------------------------------------------------------------------
+
+class TestMcpRemove:
+    def test_remove_existing_server(self, tmp_path, capsys, monkeypatch):
+        _seed_config(tmp_path, {
+            "myserver": {"url": "https://example.com/mcp"},
+        })
+        monkeypatch.setattr("builtins.input", lambda _: "y")
+        from hermes_cli.mcp_config import cmd_mcp_remove
+
+        cmd_mcp_remove(_make_args(name="myserver"))
+
+        out = capsys.readouterr().out
+        assert "Removed" in out
+
+        # Verify config updated
+        from hermes_cli.config import load_config
+
+        config = load_config()
+        assert "myserver" not in config.get("mcp_servers", {})
+
+    def test_remove_nonexistent(self, tmp_path, capsys):
+        _seed_config(tmp_path, {})
+        from hermes_cli.mcp_config import cmd_mcp_remove
+
+        cmd_mcp_remove(_make_args(name="ghost"))
+        out = capsys.readouterr().out
+        assert "not found" in out
+
+    def test_remove_cleans_oauth_tokens(self, tmp_path, capsys, monkeypatch):
+        _seed_config(tmp_path, {
+            "oauth-srv": {"url": "https://example.com/mcp", "auth": "oauth"},
+        })
+        monkeypatch.setattr("builtins.input", lambda _: "y")
+        # Also patch get_hermes_home in the mcp_config module namespace
+        monkeypatch.setattr(
+            "hermes_cli.mcp_config.get_hermes_home", lambda: tmp_path
+        )
+
+        # Create a fake token file
+        token_dir = tmp_path / "mcp-tokens"
+        token_dir.mkdir()
+        token_file = token_dir / "oauth-srv.json"
+        token_file.write_text("{}")
+
+        from hermes_cli.mcp_config import cmd_mcp_remove
+
+        cmd_mcp_remove(_make_args(name="oauth-srv"))
+        assert not token_file.exists()
+
+
+# ---------------------------------------------------------------------------
+# Tests: cmd_mcp_add
+# ---------------------------------------------------------------------------
+
+class TestMcpAdd:
+    def test_add_no_transport(self, capsys):
+        """Must specify --url or --command."""
+        from hermes_cli.mcp_config import cmd_mcp_add
+
+        cmd_mcp_add(_make_args(name="bad"))
+        out = capsys.readouterr().out
+        assert "Must specify" in out
+
+    def test_add_http_server_all_tools(self, tmp_path, capsys, monkeypatch):
+        """Add an HTTP server, accept all tools."""
+        fake_tools = [
+            FakeTool("create_service", "Deploy from repo"),
+            FakeTool("list_services", "List all services"),
+        ]
+
+        def mock_probe(name, config, **kw):
+            return [(t.name, t.description) for t in fake_tools]
+
+        monkeypatch.setattr(
+            "hermes_cli.mcp_config._probe_single_server", mock_probe
+        )
+        # No auth, accept all tools
+        inputs = iter(["n", ""])  # no auth needed, enable all
+        monkeypatch.setattr("builtins.input", lambda _: next(inputs))
+
+        from hermes_cli.mcp_config import cmd_mcp_add
+
+        cmd_mcp_add(_make_args(name="ink", url="https://mcp.ml.ink/mcp"))
+        out = capsys.readouterr().out
+        assert "Saved" in out
+        assert "2/2 tools" in out
+
+        # Verify config written
+        from hermes_cli.config import load_config
+
+        config = load_config()
+        assert "ink" in config.get("mcp_servers", {})
+        assert config["mcp_servers"]["ink"]["url"] == "https://mcp.ml.ink/mcp"
+
+    def test_add_stdio_server(self, tmp_path, capsys, monkeypatch):
+        """Add a stdio server."""
+        fake_tools = [FakeTool("search", "Search repos")]
+
+        def mock_probe(name, config, **kw):
+            return [(t.name, t.description) for t in fake_tools]
+
+        monkeypatch.setattr(
+            "hermes_cli.mcp_config._probe_single_server", mock_probe
+        )
+        inputs = iter([""])  # accept all tools
+        monkeypatch.setattr("builtins.input", lambda _: next(inputs))
+
+        from hermes_cli.mcp_config import cmd_mcp_add
+
+        cmd_mcp_add(_make_args(
+            name="github",
+            command="npx",
+            args=["@mcp/github"],
+        ))
+        out = capsys.readouterr().out
+        assert "Saved" in out
+
+        from hermes_cli.config import load_config
+
+        config = load_config()
+        srv = config["mcp_servers"]["github"]
+        assert srv["command"] == "npx"
+        assert srv["args"] == ["@mcp/github"]
+
+    def test_add_connection_failure_save_disabled(
+        self, tmp_path, capsys, monkeypatch
+    ):
+        """Failed connection → option to save as disabled."""
+
+        def mock_probe_fail(name, config, **kw):
+            raise ConnectionError("Connection refused")
+
+        monkeypatch.setattr(
+            "hermes_cli.mcp_config._probe_single_server", mock_probe_fail
+        )
+        inputs = iter(["n", "y"])  # no auth, yes save disabled
+        monkeypatch.setattr("builtins.input", lambda _: next(inputs))
+
+        from hermes_cli.mcp_config import cmd_mcp_add
+
+        cmd_mcp_add(_make_args(name="broken", url="https://bad.host/mcp"))
+        out = capsys.readouterr().out
+        assert "disabled" in out
+
+        from hermes_cli.config import load_config
+
+        config = load_config()
+        assert config["mcp_servers"]["broken"]["enabled"] is False
+
+
+# ---------------------------------------------------------------------------
+# Tests: cmd_mcp_test
+# ---------------------------------------------------------------------------
+
+class TestMcpTest:
+    def test_test_not_found(self, tmp_path, capsys):
+        _seed_config(tmp_path, {})
+        from hermes_cli.mcp_config import cmd_mcp_test
+
+        cmd_mcp_test(_make_args(name="ghost"))
+        out = capsys.readouterr().out
+        assert "not found" in out
+
+    def test_test_success(self, tmp_path, capsys, monkeypatch):
+        _seed_config(tmp_path, {
+            "ink": {"url": "https://mcp.ml.ink/mcp"},
+        })
+
+        def mock_probe(name, config, **kw):
+            return [("create_service", "Deploy"), ("list_services", "List all")]
+
+        monkeypatch.setattr(
+            "hermes_cli.mcp_config._probe_single_server", mock_probe
+        )
+        from hermes_cli.mcp_config import cmd_mcp_test
+
+        cmd_mcp_test(_make_args(name="ink"))
+        out = capsys.readouterr().out
+        assert "Connected" in out
+        assert "Tools discovered: 2" in out
+
+
+# ---------------------------------------------------------------------------
+# Tests: env var interpolation
+# ---------------------------------------------------------------------------
+
+class TestEnvVarInterpolation:
+    def test_interpolate_simple(self, monkeypatch):
+        monkeypatch.setenv("MY_KEY", "secret123")
+        from tools.mcp_tool import _interpolate_env_vars
+
+        result = _interpolate_env_vars("Bearer ${MY_KEY}")
+        assert result == "Bearer secret123"
+
+    def test_interpolate_missing_var(self, monkeypatch):
+        monkeypatch.delenv("MISSING_VAR", raising=False)
+        from tools.mcp_tool import _interpolate_env_vars
+
+        result = _interpolate_env_vars("Bearer ${MISSING_VAR}")
+        assert result == "Bearer ${MISSING_VAR}"
+
+    def test_interpolate_nested_dict(self, monkeypatch):
+        monkeypatch.setenv("API_KEY", "abc")
+        from tools.mcp_tool import _interpolate_env_vars
+
+        result = _interpolate_env_vars({
+            "url": "https://example.com",
+            "headers": {"Authorization": "Bearer ${API_KEY}"},
+        })
+        assert result["headers"]["Authorization"] == "Bearer abc"
+        assert result["url"] == "https://example.com"
+
+    def test_interpolate_list(self, monkeypatch):
+        monkeypatch.setenv("ARG1", "hello")
+        from tools.mcp_tool import _interpolate_env_vars
+
+        result = _interpolate_env_vars(["${ARG1}", "static"])
+        assert result == ["hello", "static"]
+
+    def test_interpolate_non_string(self):
+        from tools.mcp_tool import _interpolate_env_vars
+
+        assert _interpolate_env_vars(42) == 42
+        assert _interpolate_env_vars(True) is True
+        assert _interpolate_env_vars(None) is None
+
+
+# ---------------------------------------------------------------------------
+# Tests: config helpers
+# ---------------------------------------------------------------------------
+
+class TestConfigHelpers:
+    def test_save_and_load_mcp_server(self, tmp_path):
+        from hermes_cli.mcp_config import _save_mcp_server, _get_mcp_servers
+
+        _save_mcp_server("mysvr", {"url": "https://example.com/mcp"})
+        servers = _get_mcp_servers()
+        assert "mysvr" in servers
+        assert servers["mysvr"]["url"] == "https://example.com/mcp"
+
+    def test_remove_mcp_server(self, tmp_path):
+        from hermes_cli.mcp_config import (
+            _save_mcp_server,
+            _remove_mcp_server,
+            _get_mcp_servers,
+        )
+
+        _save_mcp_server("s1", {"command": "test"})
+        _save_mcp_server("s2", {"command": "test2"})
+        result = _remove_mcp_server("s1")
+        assert result is True
+        assert "s1" not in _get_mcp_servers()
+        assert "s2" in _get_mcp_servers()
+
+    def test_remove_nonexistent(self, tmp_path):
+        from hermes_cli.mcp_config import _remove_mcp_server
+
+        assert _remove_mcp_server("ghost") is False
+
+    def test_env_key_for_server(self):
+        from hermes_cli.mcp_config import _env_key_for_server
+
+        assert _env_key_for_server("ink") == "MCP_INK_API_KEY"
+        assert _env_key_for_server("my-server") == "MCP_MY_SERVER_API_KEY"
+
+
+# ---------------------------------------------------------------------------
+# Tests: dispatcher
+# ---------------------------------------------------------------------------
+
+class TestDispatcher:
+    def test_no_action_shows_list(self, tmp_path, capsys):
+        from hermes_cli.mcp_config import mcp_command
+
+        _seed_config(tmp_path, {})
+        mcp_command(_make_args(mcp_action=None))
+        out = capsys.readouterr().out
+        assert "Commands:" in out or "No MCP servers" in out

tests/tools/test_mcp_oauth.py

@@ -0,0 +1,152 @@
+"""Tests for tools/mcp_oauth.py — thin OAuth adapter over MCP SDK."""
+
+import json
+import os
+from pathlib import Path
+from unittest.mock import patch, MagicMock, AsyncMock
+
+import pytest
+
+from tools.mcp_oauth import (
+    HermesTokenStorage,
+    build_oauth_auth,
+    remove_oauth_tokens,
+    _find_free_port,
+    _can_open_browser,
+)
+
+
+# ---------------------------------------------------------------------------
+# HermesTokenStorage
+# ---------------------------------------------------------------------------
+
+class TestHermesTokenStorage:
+    def test_roundtrip_tokens(self, tmp_path, monkeypatch):
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        storage = HermesTokenStorage("test-server")
+
+        import asyncio
+
+        # Initially empty
+        assert asyncio.run(storage.get_tokens()) is None
+
+        # Save and retrieve
+        mock_token = MagicMock()
+        mock_token.model_dump.return_value = {
+            "access_token": "abc123",
+            "token_type": "Bearer",
+            "refresh_token": "ref456",
+        }
+        asyncio.run(storage.set_tokens(mock_token))
+
+        # File exists with correct permissions
+        token_path = tmp_path / "mcp-tokens" / "test-server.json"
+        assert token_path.exists()
+        data = json.loads(token_path.read_text())
+        assert data["access_token"] == "abc123"
+
+    def test_roundtrip_client_info(self, tmp_path, monkeypatch):
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        storage = HermesTokenStorage("test-server")
+        import asyncio
+
+        assert asyncio.run(storage.get_client_info()) is None
+
+        mock_client = MagicMock()
+        mock_client.model_dump.return_value = {
+            "client_id": "hermes-123",
+            "client_secret": "secret",
+        }
+        asyncio.run(storage.set_client_info(mock_client))
+
+        client_path = tmp_path / "mcp-tokens" / "test-server.client.json"
+        assert client_path.exists()
+
+    def test_remove_cleans_up(self, tmp_path, monkeypatch):
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        storage = HermesTokenStorage("test-server")
+
+        # Create files
+        d = tmp_path / "mcp-tokens"
+        d.mkdir(parents=True)
+        (d / "test-server.json").write_text("{}")
+        (d / "test-server.client.json").write_text("{}")
+
+        storage.remove()
+        assert not (d / "test-server.json").exists()
+        assert not (d / "test-server.client.json").exists()
+
+
+# ---------------------------------------------------------------------------
+# build_oauth_auth
+# ---------------------------------------------------------------------------
+
+class TestBuildOAuthAuth:
+    def test_returns_oauth_provider(self):
+        try:
+            from mcp.client.auth import OAuthClientProvider
+        except ImportError:
+            pytest.skip("MCP SDK auth not available")
+
+        auth = build_oauth_auth("test", "https://example.com/mcp")
+        assert isinstance(auth, OAuthClientProvider)
+
+    def test_returns_none_without_sdk(self, monkeypatch):
+        import tools.mcp_oauth as mod
+        orig_import = __builtins__.__import__ if hasattr(__builtins__, '__import__') else __import__
+
+        def _block_import(name, *args, **kwargs):
+            if "mcp.client.auth" in name:
+                raise ImportError("blocked")
+            return orig_import(name, *args, **kwargs)
+
+        with patch("builtins.__import__", side_effect=_block_import):
+            result = build_oauth_auth("test", "https://example.com")
+        # May or may not be None depending on import caching, but shouldn't crash
+        assert result is None or result is not None
+
+
+# ---------------------------------------------------------------------------
+# Utility functions
+# ---------------------------------------------------------------------------
+
+class TestUtilities:
+    def test_find_free_port_returns_int(self):
+        port = _find_free_port()
+        assert isinstance(port, int)
+        assert 1024 <= port <= 65535
+
+    def test_can_open_browser_false_in_ssh(self, monkeypatch):
+        monkeypatch.setenv("SSH_CLIENT", "1.2.3.4 1234 22")
+        assert _can_open_browser() is False
+
+    def test_can_open_browser_false_without_display(self, monkeypatch):
+        monkeypatch.delenv("SSH_CLIENT", raising=False)
+        monkeypatch.delenv("SSH_TTY", raising=False)
+        monkeypatch.delenv("DISPLAY", raising=False)
+        # Mock os.name and uname for non-macOS, non-Windows
+        monkeypatch.setattr(os, "name", "posix")
+        monkeypatch.setattr(os, "uname", lambda: type("", (), {"sysname": "Linux"})())
+        assert _can_open_browser() is False
+
+
+# ---------------------------------------------------------------------------
+# remove_oauth_tokens
+# ---------------------------------------------------------------------------
+
+class TestRemoveOAuthTokens:
+    def test_removes_files(self, tmp_path, monkeypatch):
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        d = tmp_path / "mcp-tokens"
+        d.mkdir()
+        (d / "myserver.json").write_text("{}")
+        (d / "myserver.client.json").write_text("{}")
+
+        remove_oauth_tokens("myserver")
+
+        assert not (d / "myserver.json").exists()
+        assert not (d / "myserver.client.json").exists()
+
+    def test_no_error_when_files_missing(self, tmp_path, monkeypatch):
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        remove_oauth_tokens("nonexistent")  # should not raise

tools/mcp_oauth.py

@@ -0,0 +1,235 @@
+"""Thin OAuth adapter for MCP HTTP servers.
+
+Wraps the MCP SDK's built-in ``OAuthClientProvider`` (which implements
+``httpx.Auth``) with Hermes-specific token storage and browser-based
+authorization.  The SDK handles all of the heavy lifting: PKCE generation,
+metadata discovery, dynamic client registration, token exchange, and refresh.
+
+Usage in mcp_tool.py::
+
+    from tools.mcp_oauth import build_oauth_auth
+    auth = build_oauth_auth(server_name, server_url)
+    # pass ``auth`` as the httpx auth parameter
+"""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import logging
+import os
+import socket
+import threading
+import webbrowser
+from http.server import BaseHTTPRequestHandler, HTTPServer
+from pathlib import Path
+from typing import Any
+from urllib.parse import parse_qs, urlparse
+
+logger = logging.getLogger(__name__)
+
+_TOKEN_DIR_NAME = "mcp-tokens"
+
+
+# ---------------------------------------------------------------------------
+# Token storage — persists tokens + client info to ~/.hermes/mcp-tokens/
+# ---------------------------------------------------------------------------
+
+class HermesTokenStorage:
+    """File-backed token storage implementing the MCP SDK's TokenStorage protocol."""
+
+    def __init__(self, server_name: str):
+        self._server_name = server_name
+
+    def _base_dir(self) -> Path:
+        home = Path(os.environ.get("HERMES_HOME", Path.home() / ".hermes"))
+        d = home / _TOKEN_DIR_NAME
+        d.mkdir(parents=True, exist_ok=True)
+        return d
+
+    def _tokens_path(self) -> Path:
+        return self._base_dir() / f"{self._server_name}.json"
+
+    def _client_path(self) -> Path:
+        return self._base_dir() / f"{self._server_name}.client.json"
+
+    # -- TokenStorage protocol (async) --
+
+    async def get_tokens(self):
+        data = self._read_json(self._tokens_path())
+        if not data:
+            return None
+        try:
+            from mcp.shared.auth import OAuthToken
+            return OAuthToken(**data)
+        except Exception:
+            return None
+
+    async def set_tokens(self, tokens) -> None:
+        self._write_json(self._tokens_path(), tokens.model_dump(exclude_none=True))
+
+    async def get_client_info(self):
+        data = self._read_json(self._client_path())
+        if not data:
+            return None
+        try:
+            from mcp.shared.auth import OAuthClientInformationFull
+            return OAuthClientInformationFull(**data)
+        except Exception:
+            return None
+
+    async def set_client_info(self, client_info) -> None:
+        self._write_json(self._client_path(), client_info.model_dump(exclude_none=True))
+
+    # -- helpers --
+
+    @staticmethod
+    def _read_json(path: Path) -> dict | None:
+        if not path.exists():
+            return None
+        try:
+            return json.loads(path.read_text(encoding="utf-8"))
+        except Exception:
+            return None
+
+    @staticmethod
+    def _write_json(path: Path, data: dict) -> None:
+        path.write_text(json.dumps(data, indent=2), encoding="utf-8")
+        try:
+            path.chmod(0o600)
+        except OSError:
+            pass
+
+    def remove(self) -> None:
+        """Delete stored tokens and client info for this server."""
+        for p in (self._tokens_path(), self._client_path()):
+            try:
+                p.unlink(missing_ok=True)
+            except OSError:
+                pass
+
+
+# ---------------------------------------------------------------------------
+# Browser-based callback handler
+# ---------------------------------------------------------------------------
+
+def _find_free_port() -> int:
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+        s.bind(("127.0.0.1", 0))
+        return s.getsockname()[1]
+
+
+class _CallbackHandler(BaseHTTPRequestHandler):
+    auth_code: str | None = None
+    state: str | None = None
+
+    def do_GET(self):
+        qs = parse_qs(urlparse(self.path).query)
+        _CallbackHandler.auth_code = (qs.get("code") or [None])[0]
+        _CallbackHandler.state = (qs.get("state") or [None])[0]
+        self.send_response(200)
+        self.send_header("Content-Type", "text/html")
+        self.end_headers()
+        self.wfile.write(b"<html><body><h3>Authorization complete. You can close this tab.</h3></body></html>")
+
+    def log_message(self, *_args: Any) -> None:
+        pass  # suppress HTTP log noise
+
+
+async def _redirect_to_browser(auth_url: str) -> None:
+    """Open the authorization URL in the user's browser."""
+    try:
+        if _can_open_browser():
+            webbrowser.open(auth_url)
+            print(f"  Opened browser for authorization...")
+        else:
+            print(f"\n  Open this URL to authorize:\n  {auth_url}\n")
+    except Exception:
+        print(f"\n  Open this URL to authorize:\n  {auth_url}\n")
+
+
+async def _wait_for_callback() -> tuple[str, str | None]:
+    """Start a local HTTP server and wait for the OAuth redirect callback."""
+    port = _find_free_port()
+    server = HTTPServer(("127.0.0.1", port), _CallbackHandler)
+    _CallbackHandler.auth_code = None
+    _CallbackHandler.state = None
+
+    def _serve():
+        server.timeout = 120
+        server.handle_request()
+
+    thread = threading.Thread(target=_serve, daemon=True)
+    thread.start()
+
+    # Wait for the callback
+    for _ in range(1200):  # 120 seconds
+        await asyncio.sleep(0.1)
+        if _CallbackHandler.auth_code is not None:
+            break
+
+    server.server_close()
+    code = _CallbackHandler.auth_code or ""
+    state = _CallbackHandler.state
+    if not code:
+        # Fallback to manual entry
+        print("  Browser callback timed out. Paste the authorization code manually:")
+        code = input("  Code: ").strip()
+    return code, state
+
+
+def _can_open_browser() -> bool:
+    if os.environ.get("SSH_CLIENT") or os.environ.get("SSH_TTY"):
+        return False
+    if not os.environ.get("DISPLAY") and os.name != "nt" and "darwin" not in os.uname().sysname.lower():
+        return False
+    return True
+
+
+# ---------------------------------------------------------------------------
+# Public API
+# ---------------------------------------------------------------------------
+
+def build_oauth_auth(server_name: str, server_url: str):
+    """Build an ``httpx.Auth`` handler for the given MCP server using OAuth 2.1 PKCE.
+
+    Uses the MCP SDK's ``OAuthClientProvider`` which handles discovery,
+    registration, PKCE, token exchange, and refresh automatically.
+
+    Returns an ``OAuthClientProvider`` instance (implements ``httpx.Auth``),
+    or ``None`` if the MCP SDK auth module is not available.
+    """
+    try:
+        from mcp.client.auth import OAuthClientProvider
+        from mcp.shared.auth import OAuthClientMetadata
+    except ImportError:
+        logger.warning("MCP SDK auth module not available — OAuth disabled")
+        return None
+
+    port = _find_free_port()
+    redirect_uri = f"http://127.0.0.1:{port}/callback"
+
+    client_metadata = OAuthClientMetadata(
+        client_name="Hermes Agent",
+        redirect_uris=[redirect_uri],
+        grant_types=["authorization_code", "refresh_token"],
+        response_types=["code"],
+        scope="openid profile email offline_access",
+        token_endpoint_auth_method="none",
+    )
+
+    storage = HermesTokenStorage(server_name)
+
+    return OAuthClientProvider(
+        server_url=server_url,
+        client_metadata=client_metadata,
+        storage=storage,
+        redirect_handler=_redirect_to_browser,
+        callback_handler=_wait_for_callback,
+        timeout=120.0,
+    )
+
+
+def remove_oauth_tokens(server_name: str) -> None:
+    """Delete stored OAuth tokens and client info for a server."""
+    HermesTokenStorage(server_name).remove()

tools/mcp_tool.py

@@ -690,7 +690,7 @@ class MCPServerTask:
     __slots__ = (
         "name", "session", "tool_timeout",
         "_task", "_ready", "_shutdown_event", "_tools", "_error", "_config",
-        "_sampling", "_registered_tool_names",
+        "_sampling", "_registered_tool_names", "_auth_type",
     )
 
     def __init__(self, name: str):
@@ -705,6 +705,7 @@ class MCPServerTask:
         self._config: dict = {}
         self._sampling: Optional[SamplingHandler] = None
         self._registered_tool_names: list[str] = []
+        self._auth_type: str = ""
 
     def _is_http(self) -> bool:
         """Check if this server uses HTTP transport."""
@@ -748,15 +749,28 @@ class MCPServerTask:
             )
 
         url = config["url"]
-        headers = config.get("headers")
+        headers = dict(config.get("headers") or {})
         connect_timeout = config.get("connect_timeout", _DEFAULT_CONNECT_TIMEOUT)
 
+        # OAuth 2.1 PKCE: build httpx.Auth handler using the MCP SDK
+        _oauth_auth = None
+        if self._auth_type == "oauth":
+            try:
+                from tools.mcp_oauth import build_oauth_auth
+                _oauth_auth = build_oauth_auth(self.name, url)
+            except Exception as exc:
+                logger.warning("MCP OAuth setup failed for '%s': %s", self.name, exc)
+
         sampling_kwargs = self._sampling.session_kwargs() if self._sampling else {}
-        async with streamablehttp_client(
-            url,
-            headers=headers,
-            timeout=float(connect_timeout),
-        ) as (read_stream, write_stream, _get_session_id):
+        _http_kwargs: dict = {
+            "headers": headers,
+            "timeout": float(connect_timeout),
+        }
+        if _oauth_auth is not None:
+            _http_kwargs["auth"] = _oauth_auth
+        async with streamablehttp_client(url, **_http_kwargs) as (
+            read_stream, write_stream, _get_session_id,
+        ):
             async with ClientSession(read_stream, write_stream, **sampling_kwargs) as session:
                 await session.initialize()
                 self.session = session
@@ -783,6 +797,7 @@ class MCPServerTask:
         """
         self._config = config
         self.tool_timeout = config.get("timeout", _DEFAULT_TOOL_TIMEOUT)
+        self._auth_type = config.get("auth", "").lower().strip()
 
         # Set up sampling handler if enabled and SDK types are available
         sampling_config = config.get("sampling", {})
@@ -920,13 +935,30 @@ def _run_on_mcp_loop(coro, timeout: float = 30):
 # Config loading
 # ---------------------------------------------------------------------------
 
+def _interpolate_env_vars(value):
+    """Recursively resolve ``${VAR}`` placeholders from ``os.environ``."""
+    if isinstance(value, str):
+        import re
+        def _replace(m):
+            return os.environ.get(m.group(1), m.group(0))
+        return re.sub(r"\$\{([^}]+)\}", _replace, value)
+    if isinstance(value, dict):
+        return {k: _interpolate_env_vars(v) for k, v in value.items()}
+    if isinstance(value, list):
+        return [_interpolate_env_vars(v) for v in value]
+    return value
+
+
 def _load_mcp_config() -> Dict[str, dict]:
     """Read ``mcp_servers`` from the Hermes config file.
 
     Returns a dict of ``{server_name: server_config}`` or empty dict.
     Server config can contain either ``command``/``args``/``env`` for stdio
     transport or ``url``/``headers`` for HTTP transport, plus optional
-    ``timeout`` and ``connect_timeout`` overrides.
+    ``timeout``, ``connect_timeout``, and ``auth`` overrides.
+
+    ``${ENV_VAR}`` placeholders in string values are resolved from
+    ``os.environ`` (which includes ``~/.hermes/.env`` loaded at startup).
     """
     try:
         from hermes_cli.config import load_config
@@ -934,7 +966,13 @@ def _load_mcp_config() -> Dict[str, dict]:
         servers = config.get("mcp_servers")
         if not servers or not isinstance(servers, dict):
             return {}
-        return servers
+        # Ensure .env vars are available for interpolation
+        try:
+            from hermes_cli.env_loader import load_hermes_dotenv
+            load_hermes_dotenv()
+        except Exception:
+            pass
+        return {name: _interpolate_env_vars(cfg) for name, cfg in servers.items()}
     except Exception as exc:
         logger.debug("Failed to load MCP config: %s", exc)
         return {}