Open-source tool MCP Verdict tests how MCP servers behave when tools fail

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A developer has released MCP Verdict v0.1.0, an open-source Python command-line tool for testing failure behavior in Model Context Protocol (MCP) servers. The tool lets users define expected outcomes in YAML and checks whether a server's actual responses match, including cases where a tool fails but reports success. Its first release supports STDIO and Streamable HTTP transports, verifies tool errors via the isError field, and tests HTTP 401 and 403 authentication responses. It also produces JSON reports and CI-friendly exit codes, and it is available on PyPI for Python 3.11 and 3.12. The author notes it is not a comprehensive security scanner and is intended mainly to make failure scenarios reproducible and catch regressions.

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