>_ SNS-MyAgent

MCP (Model Context Protocol)

Purpose

Connect external tool servers to the agent - filesystem, GitHub, databases, web search - over the Model Context Protocol, so the model can call tools the agent doesn’t ship itself.

How it works

  • Config lives in per-project .mcp.json plus user-level sources, loaded via the capability system (src/mcp/config.ts → loadCapability).
  • Servers run over two transports: stdio (command) and HTTP (url); src/mcp/json-rpc.ts provides a lightweight HTTP JSON-RPC path and SSE parsing.
  • OAuth support: src/mcp/oauth-discovery.ts, oauth-flow.ts, oauth-credentials.ts, plus Smithery auth (smithery-auth.ts).
  • Tool bridge + cache expose MCP tools to the agent loop (src/mcp/tool-bridge.ts, tool-cache.ts).
  • Exa/browser filters can exclude servers whose functionality the builtin tools already provide.

Configuration

Servers are added through conversation, /mcp add, or hand-editing:

/mcp add <name> [--scope project|user] [--url <url>] [-- <command...>]
/mcp list
/mcp remove <name> [--scope project|user]
/mcp test <name>            # verify the connection
/mcp reauth <name>          # re-run OAuth flow
/mcp disable <name>; /mcp enable <name>
/mcp smithery-search <keyword> [--scope project|user] [--limit n] [--semantic]

Through conversation:

> add MCP filesystem for /home/user/projects
> add MCP github

The agent writes the server into .mcp.json via src/mcp/config-writer.ts.

Real example

> add MCP filesystem for /home/user/projects
> list my files (agent calls filesystem MCP server tools)
> /mcp list
  • filesystem (stdio, project)
> /mcp test filesystem

Failure behavior

  • A server that fails to start or authenticate is reported by /mcp test; the agent degrades gracefully (that server’s tools disappear from tool cache).
  • Missing OAuth credentials route to the OAuth flow (/mcp reauth), or return an auth error for HTTP servers.

Limitations

  • Server tools are only available when the server is enabled and reachable at session start; dynamic reconnect is not guaranteed.
  • Not all servers ship with a manual OAuth flow; Smithery-backed servers use their own auth path.