# MCP Client Capabilities

A maintained JSON database of every known Model Context Protocol client and which protocol features each one supports, so an MCP server can decide how to respond without relying only on the handshake.

MCP Client Capabilities aims to be an up-to-date database of every known Model Context Protocol client and its capabilities, published as a single JSON file so it can be read from any programming language while still supporting TypeScript type safety for its npm package. It exists because the protocol's own capability negotiation during the initial handshake does not give a server enough information to provide the best experience for a given client.

Each client is listed once, describing the latest publicly available release, with fields for whether it supports resources, prompts, tools, discovery, sampling, tasks, roots and the two forms of elicitation, plus the protocol version that record was checked against. A server is expected to prioritize whatever the client's own initialize request reports over this file, and to ignore the file's data entirely if the client's reported protocol version does not match the version recorded here, since that signals the entry may be out of date.

Website: https://github.com/apify/mcp-client-capabilities