MCP tool deadlines do not send protocol cancellation

Kit's MCP wrapper can stop its local wait at the configured tool deadline, but the AgentKit MCP adapter exposes only an awaited call_tool future, not RMCP's RequestHandle. Dropping that future does not invoke RequestHandle::cancel, so Kit cannot send notifications/cancelled for the timed-out request. A server that never answers can retain the corresponding local RMCP pending request until the connection closes, and a remote side effect may still complete. Kit therefore warns callers to inspect remote state before retrying side effects.

A complete fix belongs at the AgentKit MCP boundary: expose a per-call deadline or cancellation-aware call API that uses RMCP PeerRequestOptions/RequestHandle, sends protocol cancellation on expiry, unregisters pending request state, and returns a typed timeout error. Kit can then delegate its timeout_seconds policy to that API instead of enforcing only the outer local deadline.

Relevant implementation: Kit src/tools/mcp.rs (McpTool::dispatch), AgentKit agentkit-mcp (McpConnection::call_tool), and RMCP RequestHandle.

Trace Kit’s src/tools/mcp.rs at McpTool::dispatch, then read agentkit-mcp’s McpConnection::call_tool and RMCP’s RequestHandle/PeerRequestOptions. Verify how the awaited future currently handles deadlines, and consider the boundary behavior needed for protocol cancellation, pending-state cleanup, and a typed timeout error before Kit delegates its timeout policy there.