mcpsnoop is a transparent proxy and terminal interface for inspecting the real Model Context Protocol (MCP) traffic between AI clients and MCP servers.
It sits directly in the data path, capturing JSON-RPC frames so you can debug tool calls, capability negotiation, slow or hung requests, and unexpected arguments.
This is free and open source software.
Key Features
- Displays live JSON-RPC requests, responses, notifications, and server stderr.
- Captures the actual traffic exchanged between an AI client and MCP server.
- Replays captured tool calls against a fresh server instance.
- Inspects capabilities negotiated between the client and server.
- Provides pretty-printed JSON frame inspection with search.
- Flags slow, failed, pending, and hung calls.
- Filters traffic by tool, method, request ID, direction, frame type, status, or text.
- Exports sessions in JSON, HTML, and plain text formats.
- Supports stdio and streamable HTTP MCP servers.
- Offers optional key-based redaction of secrets from captured trace copies.
Website: github.com/kerlenton/mcpsnoop
Support:
Developer: Semyon Usachev
License: MIT License
mcpsnoop is written in Go. Learn Go with our recommended free books and free tutorials.
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