mcp-client-capabilities

This MCP server provides a centralized, up-to-date JSON database of MCP clients and their capabilities. It ships a single file, mcp-clients.json, which lists known MCP clients along with metadata such as display name, homepage URL, the protocol version they use, and which capabilities they support (resources, prompts, tools, discovery, sampling, roots, elicitation, etc.). Servers can consult this data during client handshakes to better tailor responses to a client’s capabilities and negotiate feature support accordingly. To use it in your MCP server, install the npm package and load the JSON data at runtime, then reference the capabilities of a given client by name and protocol version to ensure you’re aligning with the client’s reported features. The package serves as a programmatic, language-agnostic source of truth that servers can consume directly or export into their own capability caches.

Typical usage flow: install the package, import or require the mcp-clients.json data, and when a client connects, look up the client by the name reported in the initialize request (params.clientInfo.name). Verify the protocolVersion matches the one in the JSON entry; if not, fall back to existing server capabilities. Use the retrieved capabilities to construct appropriate prompts, resource access patterns, tools exposure, and any sampling or discovery behavior supported by that client. Since the data represents the latest publicly available release per client name, you should periodically refresh your data by updating the package version to keep capabilities in sync with new client releases.

Prerequisites:

• Node.js (LTS) and npm installed on your system
• Access to a terminal or shell

Installation steps:

1. Install the package locally in your project: npm install mcp-client-capabilities

2. (Optional) Install globally to access via CLI or npx without adding to your project: npm install -g mcp-client-capabilities

3. Update in the future to refresh the data with the latest known capabilities: npm update mcp-client-capabilities

4. Verify installation by listing the package files (Node.js project): node -e "console.log(require('mcp-client-capabilities'))" 2>/dev/null || echo 'Package loaded or path is invalid'

Usage example (Node.js):

const capabilities = require('mcp-client-capabilities'); console.log(capabilities);

If you’re using npx to run directly:

• Ensure you have network access and the package is published on npm registry.
• Run: npx -y mcp-client-capabilities

Note: The package provides a JSON data file (mcp-clients.json). Your server should read and cache this JSON at startup or refresh it periodically to stay aligned with current client capabilities.

Tips and considerations:

• The data in mcp-clients.json should be treated as a best-effort reference and should be overridden by the client capabilities provided in the initialize handshake (params.capabilities) for accuracy.
• Protocol version matching is important: if the incoming client’s protocolVersion does not match the version in the JSON, ignore the external data for that client to avoid misinterpretation.
• This package focuses on a centralized capability catalog; for servers with strict capability requirements, implement a fallback strategy if a client is missing certain fields.
• When integrating into a multi-language MCP server, export the JSON data into your language’s native data structures to simplify access and type safety.
• If you rely on updated client information, periodically re-install or re-fetch the package to incorporate new client entries or updated capabilities.