Guard Core

An MCP server that lets AI coding agents answer questions about the Guard security ecosystem from the libraries themselves, instead of from memory.

Covers fastapi-guard, guard-core and guard-agent.

Why

Your agent can already read the docs. What it cannot do is tell you that the redis_failopen in your config is silently doing nothing because the real field is redis_fail_open, or that the flag you are reaching for did not exist until guard-core 3.5.0, or whether a given request would actually be blocked and by which pattern.

This server answers those from the installed package: real pydantic validation, real field metadata, and the real detection engine.

Install

Install it into your project's environment, not as an isolated tool:

uv add --dev guard-core-mcp
claude mcp add guard-core -- uv run guard-core-mcp

uvx guard-core-mcp will start, but an isolated environment contains no guard-core or fastapi-guard for it to introspect, so it can only answer from bundled documentation. Running it inside your own environment is what makes the answers match the versions you actually ship.

Tools

Tool	Answers
versions	Which Guard libraries are installed here, and at what version
validate_config	Is this config valid — including typo'd keys pydantic silently ignores
config_fields	What is this setting, what does it default to, does a setting for X exist
search_docs	Where do the docs cover this
get_doc	The full text of one documentation page
check_payload	Would this request be blocked, and by which pattern

Licence

MIT