mcpsnoop shows real MCP tool calls while an AI app runs
mcpsnoop is a transparent proxy placed between an AI client and an . It shows the real and replies passing between apps such as , Cursor, or Claude Code and the server, live in a terminal. The official connects as a separate client, so it can miss what the real client did or failed to do.
mcpsnoop sits in the actual path and displays JSON-RPC requests, , , and server error output. For a normal server, the server launch command is wrapped with mcpsnoop --; for a server reached through a web address, mcpsnoop can sit in front and forward traffic to the original server. It can replay one captured against a fresh server copy, inspect the features agreed at startup, show full JSON frames, flag pending, slow, and failed calls, and filter the stream by tool, status, direction, method, ID, or text.
Installation is available through Go, Homebrew, or prebuilt release files. Because it runs the server command it wraps, untrusted servers should be handled in an isolated environment.
Key points
- It shows real requests and replies between an AI client and an in a terminal.
- A normal server can be wrapped by putting mcpsnoop -- before the usual server command.
- A web-address based server can be tracked by placing mcpsnoop in front of it and forwarding traffic.
- One captured can be replayed to reproduce and fix problems faster.
- Slow calls, stuck calls, errors, and agreed startup features can be inspected and filtered.