When discover_mcp_tools() is called multiple times (e.g. direct call
then model_tools import), return existing tool names instead of opening
new connections that would orphan the previous ones.
Refactor MCP connections from AsyncExitStack to task-per-server
architecture. Each server now runs as a long-lived asyncio Task
with `async with stdio_client(...)`, ensuring anyio cancel-scope
cleanup happens in the same Task that opened the connection.
Connect to external MCP servers via stdio transport, discover their tools
at startup, and register them into the hermes-agent tool registry.
- New tools/mcp_tool.py: config loading, server connection via background
event loop, tool handler factories, discovery, and graceful shutdown
- model_tools.py: trigger MCP discovery after built-in tool imports
- cli.py: call shutdown_mcp_servers in _run_cleanup
- pyproject.toml: add mcp>=1.2.0 as optional dependency
- 27 unit tests covering config, schema conversion, handlers, registration,
SDK interaction, toolset injection, graceful fallback, and shutdown
Config format (in ~/.hermes/config.yaml):
mcp_servers:
filesystem:
command: "npx"
args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
