`src/mcp/server.rs` — the MCP server side [feature: mcp]

Serve a ToolRegistry over MCP — your tools become usable by any MCP client. Exposes rmcp types deliberately (you’re embedding a real server).

Key items

• McpServerAdapter::new(registry, context, server_name, server_version) — Clone; snapshot semantics (rebuild for a different tool set).
• serve_stdio(self) — the canonical interactive transport; the returned RunningService has completed the handshake; .waiting() blocks until stdin closes; cancel via its token. Other transports: adapter.serve(transport) via rmcp’s ServiceExt.

Behavior notes

• Advertises the tools capability only (no resources/prompts/sampling/logging; no listChanged).
• list_tools maps every schema through the validation layer (see convert.rs) — invalid-schema tools are omitted with a warning, external $refs are refused (never fetched).
• call_tool: unknown name → MCP METHOD_NOT_FOUND naming what is registered; everything the tool reports (soft error, hard failure, cancellation) is a tool-level is_error result.
• Cancellation drops in-flight tool futures — served tools must be cancellation-safe.

Deep dive: MCP.