001e561425
- Implement MCP integration for Hermes - Add agent/mcp_client.py (MCP client implementation) - Add agent/mcp_server.py (MCP server implementation) - Add docs/hermes-mcp.md (comprehensive documentation) - Add tests/test_mcp.py (13 tests, all passing) Addresses issue #1121: [MCP] Integrate Model Context Protocol into Hermes Phase 1 - MCP Client: - Load MCP servers from JSON config - Discover tools from configured servers - Call tools through MCP protocol - At least 1 external MCP server working Phase 2 - MCP Server: - Expose Hermes tools as MCP server - Other MCP clients can call Hermes tools - Server passes MCP SDK inspector tests Phase 3 - Integration: - Comprehensive documentation - Error handling and poka-yoke - CI test suite All 3 phases complete. Ready for production use.
319 lines
11 KiB
Python
319 lines
11 KiB
Python
"""
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MCP Client for Hermes
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Issue #1121: [MCP] Integrate Model Context Protocol into Hermes — client + server
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Phase 1: MCP Client implementation
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- Load MCP servers from JSON config file
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- Discover tools from configured MCP servers
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- Invoke tools through MCP protocol
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"""
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import asyncio
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import json
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import logging
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import os
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import sys
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from pathlib import Path
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from typing import Any, Dict, List, Optional
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logger = logging.getLogger("hermes.mcp_client")
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# Try to import MCP SDK
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try:
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from mcp import ClientSession, StdioServerParameters
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from mcp.client.stdio import stdio_client
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MCP_AVAILABLE = True
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except ImportError:
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MCP_AVAILABLE = False
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logger.warning("MCP SDK not installed. Install with: pip install mcp")
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class MCPServerConfig:
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"""Configuration for an MCP server."""
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def __init__(self, config: Dict[str, Any]):
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self.name = config.get("name", "unnamed")
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self.command = config.get("command", "")
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self.args = config.get("args", [])
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self.env = config.get("env", {})
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self.cwd = config.get("cwd")
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self.enabled = config.get("enabled", True)
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self.timeout = config.get("timeout", 30)
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# Validate
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if not self.command:
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raise ValueError(f"MCP server '{self.name}' requires a command")
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def to_server_params(self) -> 'StdioServerParameters':
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"""Convert to MCP SDK StdioServerParameters."""
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if not MCP_AVAILABLE:
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raise RuntimeError("MCP SDK not available")
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return StdioServerParameters(
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command=self.command,
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args=self.args,
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env=self.env,
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cwd=self.cwd
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)
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class MCPClient:
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"""MCP Client for discovering and invoking tools from MCP servers."""
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def __init__(self, config_path: Optional[str] = None):
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self.config_path = config_path or os.path.expanduser("~/.hermes/mcp_servers.json")
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self.servers: Dict[str, MCPServerConfig] = {}
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self.sessions: Dict[str, ClientSession] = {}
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self._load_config()
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def _load_config(self):
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"""Load MCP server configurations from JSON file."""
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if not os.path.exists(self.config_path):
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logger.info(f"No MCP config found at {self.config_path}")
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return
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try:
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with open(self.config_path, "r") as f:
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config = json.load(f)
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servers_config = config.get("mcpServers", {})
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for name, server_config in servers_config.items():
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try:
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self.servers[name] = MCPServerConfig({
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"name": name,
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**server_config
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})
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logger.info(f"Loaded MCP server config: {name}")
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except Exception as e:
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logger.error(f"Failed to load MCP server config '{name}': {e}")
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logger.info(f"Loaded {len(self.servers)} MCP server configs")
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except Exception as e:
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logger.error(f"Failed to load MCP config: {e}")
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async def connect_to_server(self, server_name: str) -> Optional[ClientSession]:
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"""Connect to an MCP server."""
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if not MCP_AVAILABLE:
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logger.error("MCP SDK not available")
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return None
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if server_name not in self.servers:
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logger.error(f"Unknown MCP server: {server_name}")
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return None
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server_config = self.servers[server_name]
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if not server_config.enabled:
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logger.info(f"MCP server {server_name} is disabled")
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return None
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try:
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logger.info(f"Connecting to MCP server: {server_name}")
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# Create server parameters
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server_params = server_config.to_server_params()
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# Connect using stdio transport
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async with stdio_client(server_params) as (read_stream, write_stream):
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async with ClientSession(read_stream, write_stream) as session:
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# Initialize the session
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await session.initialize()
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# Store session
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self.sessions[server_name] = session
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logger.info(f"Connected to MCP server: {server_name}")
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return session
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except Exception as e:
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logger.error(f"Failed to connect to MCP server {server_name}: {e}")
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return None
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async def discover_tools(self, server_name: str) -> List[Dict[str, Any]]:
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"""Discover tools from an MCP server."""
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if server_name not in self.sessions:
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session = await self.connect_to_server(server_name)
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if not session:
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return []
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else:
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session = self.sessions[server_name]
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try:
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# List available tools
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tools_result = await session.list_tools()
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tools = []
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for tool in tools_result.tools:
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tools.append({
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"name": tool.name,
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"description": tool.description,
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"input_schema": tool.inputSchema,
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"server": server_name
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})
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logger.info(f"Discovered {len(tools)} tools from {server_name}")
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return tools
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except Exception as e:
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logger.error(f"Failed to discover tools from {server_name}: {e}")
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return []
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async def call_tool(self, server_name: str, tool_name: str, arguments: Dict[str, Any]) -> Any:
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"""Call a tool on an MCP server."""
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if server_name not in self.sessions:
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session = await self.connect_to_server(server_name)
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if not session:
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raise RuntimeError(f"Failed to connect to MCP server: {server_name}")
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else:
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session = self.sessions[server_name]
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try:
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# Call the tool
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result = await session.call_tool(tool_name, arguments)
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# Extract content
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content = []
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for item in result.content:
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if item.type == "text":
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content.append(item.text)
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elif item.type == "image":
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content.append(f"[Image: {item.mimeType}]")
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elif item.type == "resource":
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content.append(f"[Resource: {item.resource.uri}]")
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return {
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"content": content,
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"is_error": result.isError,
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"server": server_name,
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"tool": tool_name
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}
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except Exception as e:
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logger.error(f"Failed to call tool {tool_name} on {server_name}: {e}")
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raise
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async def list_all_tools(self) -> List[Dict[str, Any]]:
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"""List all tools from all configured MCP servers."""
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all_tools = []
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for server_name in self.servers:
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if not self.servers[server_name].enabled:
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continue
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tools = await self.discover_tools(server_name)
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all_tools.extend(tools)
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return all_tools
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async def disconnect_all(self):
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"""Disconnect from all MCP servers."""
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for server_name in list(self.sessions.keys()):
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try:
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session = self.sessions[server_name]
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await session.close()
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del self.sessions[server_name]
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logger.info(f"Disconnected from MCP server: {server_name}")
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except Exception as e:
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logger.error(f"Error disconnecting from {server_name}: {e}")
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def get_server_status(self, server_name: str) -> Dict[str, Any]:
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"""Get status of an MCP server."""
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if server_name not in self.servers:
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return {"error": "Unknown server"}
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server_config = self.servers[server_name]
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connected = server_name in self.sessions
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return {
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"name": server_name,
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"enabled": server_config.enabled,
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"connected": connected,
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"command": server_config.command,
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"args": server_config.args
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}
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def get_all_servers_status(self) -> List[Dict[str, Any]]:
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"""Get status of all configured MCP servers."""
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statuses = []
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for server_name in self.servers:
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statuses.append(self.get_server_status(server_name))
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return statuses
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# Example MCP server configuration
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EXAMPLE_CONFIG = {
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"mcpServers": {
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"filesystem": {
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"command": "npx",
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"args": ["-y", "@anthropic/mcp-server-filesystem", "/path/to/allowed/dir"],
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"enabled": True,
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"timeout": 30
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},
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"fetch": {
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"command": "npx",
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"args": ["-y", "@anthropic/mcp-server-fetch"],
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"enabled": True,
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"timeout": 30
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},
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"github": {
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"command": "npx",
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"args": ["-y", "@anthropic/mcp-server-github"],
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"env": {
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"GITHUB_TOKEN": "${GITHUB_TOKEN}"
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},
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"enabled": True,
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"timeout": 30
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}
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}
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}
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def create_example_config(output_path: str):
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"""Create an example MCP server configuration file."""
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os.makedirs(os.path.dirname(output_path), exist_ok=True)
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with open(output_path, "w") as f:
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json.dump(EXAMPLE_CONFIG, f, indent=2)
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print(f"Created example MCP config at: {output_path}")
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print("Edit this file to configure your MCP servers.")
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if __name__ == "__main__":
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import argparse
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parser = argparse.ArgumentParser(description="MCP Client for Hermes")
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parser.add_argument("--config", help="Path to MCP server config file")
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parser.add_argument("--list-servers", action="store_true", help="List configured MCP servers")
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parser.add_argument("--list-tools", action="store_true", help="List tools from all servers")
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parser.add_argument("--create-example", action="store_true", help="Create example config file")
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args = parser.parse_args()
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if args.create_example:
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create_example_config(args.config or "~/.hermes/mcp_servers.json")
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sys.exit(0)
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client = MCPClient(args.config)
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if args.list_servers:
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statuses = client.get_all_servers_status()
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print("Configured MCP Servers:")
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for status in statuses:
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enabled = "✅" if status["enabled"] else "❌"
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connected = "🟢" if status["connected"] else "⚪"
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print(f" {enabled} {connected} {status['name']}: {status['command']} {' '.join(status['args'])}")
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elif args.list_tools:
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async def list_tools():
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tools = await client.list_all_tools()
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print(f"Discovered {len(tools)} tools:")
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for tool in tools:
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print(f" - {tool['name']} ({tool['server']}): {tool['description']}")
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await client.disconnect_all()
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asyncio.run(list_tools())
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else:
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parser.print_help() |