ABOUT

A focused checker for a new MCP extension.

MCP App Ready is an independent, free developer utility for reviewing MCP Apps tool metadata, UI resource declarations, HTML content and sandbox policy before runtime testing.

Why it exists

Generic JSON validation cannot prove that a tool references an available ui:// resource, that the resource uses the MCP App MIME profile, or that its CSP fields contain usable origins. This site makes those cross-object relationships visible.

Editorial approach

Rules are based on the stable 2026-01-26 MCP Apps specification. Additional security and interoperability guidance is labeled as an independent check rather than an official conformance claim.

Limitations

The checker does not connect to your MCP server, execute HTML, simulate every host or certify security. Follow static validation with the official conformance tooling and real host tests.

Open source

Source and issue tracking are available on GitHub.