open-feature/mcp

OpenFeature MCP

Warning

This project is in active development.

Features

A local Model Context Protocol (MCP) server that provides OpenFeature SDK installation guidance and Open Feature Remote Evaluation Protocol (OFREP) over stdio.

• OpenFeature SDK Installation Guides: Fetch installation prompts for various OpenFeature SDKs
• MCP stdio Transport: Intended for local usage by MCP-compatible clients

This server is published to the MCP Registry under dev.openfeature/mcp.

Configure your AI client (local)

Cursor

Add to ~/.cursor/mcp_settings.json:

{
  "mcpServers": {
    "OpenFeature": {
      "command": "npx",
      "args": ["-y", "@openfeature/mcp"]
    }
  }
}

VS Code (Continue)

Add to .continue/config.json:

{
  "mcpServers": {
    "OpenFeature": {
      "command": "npx",
      "args": ["-y", "@openfeature/mcp"]
    }
  }
}

Claude Code (CLI)

Add the server via CLI:

claude mcp add --transport stdio openfeature npx -y @openfeature/mcp

Then manage the connection in the CLI with /mcp.

Windsurf

In the "Manage MCP servers" raw config, add:

{
  "mcpServers": {
    "OpenFeature": {
      "command": "npx",
      "args": ["-y", "@openfeature/mcp"]
    }
  }
}

Claude Desktop

Edit your Claude Desktop config and add:

{
  "mcpServers": {
    "openfeature": {
      "command": "npx",
      "args": ["-y", "@openfeature/mcp"]
    }
  }
}

Restart Claude Desktop after saving.

NPM Global install (optional)

If you prefer a global install instead of NPX:

npm install -g @openfeature/mcp

Now in your MCP config use openfeature-mcp as the command:

{
  "mcpServers": {
    "openfeature": {
      "command": "openfeature-mcp"
    }
  }
}

All logs are written to stderr. The MCP protocol messages use stdout.

Available Tools

install_openfeature_sdk

Fetches Markdown instructions for installing the OpenFeature SDK for a given technology. Optionally augments the prompt with installation guidance for one or more feature flag providers.

Parameters:

• technology (string enum): One of the supported technologies listed below
• providers (string array, optional): Zero or more provider identifiers. If present, adds provider-specific installation notes to the prompt (or removes placeholder sections when empty).

Supported Technologies:

The technologies list is build from the avaliable prompts/*.md, updated automatically using scripts/build-prompts.js

• android
• dotnet
• go
• ios
• java
• javascript
• nestjs
• nodejs
• php
• python
• react
• ruby

Supported Providers:

The provider list is sourced automatically from the OpenFeature open-feature/openfeature.dev repo; newly added providers there become available here without manual edits. See scripts/build-providers.js for details.

ofrep_flag_eval

Evaluate feature flags via OpenFeature Remote Evaluation Protocol (OFREP). If flag_key is omitted, performs bulk evaluation.

References: open-feature/protocol repo, OFREP OpenAPI spec

Parameters (all optional unless noted):

• base_url (string, optional): Base URL of your OFREP-compatible flag service. If omitted, the server uses env/config (see below).
• flag_key (string, optional): If provided, calls single flag evaluation: /ofrep/v1/evaluate/flags/{key}. If omitted, calls bulk: /ofrep/v1/evaluate/flags.
• context (object, optional): Evaluation context, e.g. { "targetingKey": "user-123", ... }.
• etag (string, optional): For bulk requests, sent as If-None-Match to enable 304 caching semantics.
• auth (object, optional): Inline auth for this call only.
  • bearer_token (string, optional): Sets Authorization: Bearer <token>.
  • api_key (string, optional): Sets X-API-Key: <key>.

Auth and base URL resolution (priority):

1. Tool call args: base_url, auth.bearer_token, auth.api_key
2. Environment variables: OPENFEATURE_OFREP_BASE_URL (or OFREP_BASE_URL), OPENFEATURE_OFREP_BEARER_TOKEN (or OFREP_BEARER_TOKEN), OPENFEATURE_OFREP_API_KEY (or OFREP_API_KEY)
3. Config file: ~/.openfeature-mcp.json (override with OPENFEATURE_MCP_CONFIG_PATH)

Example ~/.openfeature-mcp.json:

{
  "OFREP": {
    "baseUrl": "https://flags.example.com",
    "bearerToken": "<token>",
    "apiKey": "<key>"
  }
}

Notes:

• Bulk requests may return ETag. Pass it back via etag to leverage 304 Not Modified.
• Either bearer token or API key can be supplied; both are supported by the spec.

Development

Prerequisites

• Node.js 18+

Setup

1. Install dependencies:

   npm install
   

2. Add or edit install guides in the prompts/ folder (Markdown). These are bundled at build time.

3. Build prompts bundle:

   npm run build-prompts
   

4. Build TypeScript:

   npm run build
   

5. Run locally (binary entrypoint):

   node dist/cli.js