DISCOVERY SIGNALS · LIVE FROM THE INDEX

Which APIs have a .well-known/mcp.json manifest?

5%

of the APIs in the Discry Index serve an MCP manifest at /.well-known/mcp.json.

18 pass30 partial347 failof 395 scanned

What this signal is

The MCP manifest at /.well-known/mcp.json is a discovery artifact: a fixed, predictable path where an agent can learn that an MCP server exists and how to connect, without any registry lookup.

Well-known paths are how machines find things without being told. Publishing the manifest costs a static file; omitting it means your MCP server is only discoverable to agents that already know about it.

Definition →How to ship it →

Notable passes and misses

This is the emptiest signal in the Index — and therefore the cheapest differentiation available. Resend and Pinecone serve a manifest at the well-known path; nearly every other API in the corpus, including those that already run MCP servers, does not. The gap between MCP-registry adoption and manifest adoption shows most producers list their server in catalogs but skip self-hosted discovery.

Every API, checked

395 APIs
Pass18
Partial30
Fail347
Show the other 317

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Check data assessed under Discry methodology 3.0.0 · Methodology