LaunchDarkly MCP Server

A Model Context Protocol (MCP) server for managing LaunchDarkly feature flags. Uses session-based authentication (email/password) with direct API calls — no external dependencies beyond the MCP SDK.

Features

• Feature Flags: List, search, create, delete, toggle ON/OFF
• Targeting Rules: Add rules with clauses (in, contains, segmentMatch, etc.)
• Segments: List and inspect segments
• Multi-environment: Operate on any environment (production, test, etc.)
• Semantic Patch: Full support for LaunchDarkly's semantic patch API
• Auto re-auth: Automatically re-authenticates if session expires

Environment Variables

| Variable | Required | Default | Description | |----------|----------|---------|-------------| | LAUNCHDARKLY_EMAIL | Yes | — | Account email | | LAUNCHDARKLY_PASSWORD | Yes | — | Account password | | LAUNCHDARKLY_BASE_URL | No | https://app.launchdarkly.com | LaunchDarkly base URL | | LAUNCHDARKLY_PROJECT | No | default | Default project key | | LAUNCHDARKLY_ENVIRONMENT | No | production | Default environment key |

Cursor IDE Integration

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "launchdarkly": {
      "command": "node",
      "args": ["packages/launchdarkly/dist/index.js"],
      "env": {
        "LAUNCHDARKLY_EMAIL": "[email protected]",
        "LAUNCHDARKLY_PASSWORD": "your-password",
        "LAUNCHDARKLY_PROJECT": "default",
        "LAUNCHDARKLY_ENVIRONMENT": "production"
      }
    }
  }
}

Available MCP Tools

Flags

| Tool | Description | |------|-------------| | list_flags | List flags with pagination, filtering, and sorting | | get_flag | Get detailed flag info (variations, rules, targeting) | | search_flags | Search flags by name or key | | create_flag | Create a new boolean feature flag | | delete_flag | Permanently delete a flag | | toggle_flag | Turn a flag ON or OFF in a specific environment | | get_flag_statuses | Get evaluation status of specific flags |

Targeting

| Tool | Description | |------|-------------| | add_flag_rule | Add a targeting rule with clauses and variation | | update_flag_targeting | Send raw semantic patch instructions (advanced) |

Segments

| Tool | Description | |------|-------------| | list_segments | List segments in a project/environment | | get_segment | Get segment details including rules |

Project

| Tool | Description | |------|-------------| | list_projects | List all projects | | list_environments | List environments in a project |

Targeting Rule Operators

The add_flag_rule tool supports these clause operators:

| Operator | Description | Example | |----------|-------------|---------| | in | Exact match | access_token in ["TOKEN1", "TOKEN2"] | | contains | String contains | email contains "@company.com" | | startsWith | String starts with | name startsWith "admin" | | endsWith | String ends with | domain endsWith ".edu" | | matches | Regex match | key matches "^test-.*" | | lessThan | Numeric less than | age lessThan 18 | | greaterThanOrEqual | Numeric gte | score greaterThanOrEqual 100 | | segmentMatch | In segment | Context in segment "beta-users" |

Development

pnpm install
pnpm dev       # Run with tsx
pnpm build     # Compile TypeScript
pnpm lint      # Run ESLint
pnpm test      # Run tests

Architecture

• LaunchDarklyClient: Handles login (2-step cookie auth) and API requests
• LaunchDarklyMCPTools: Tool implementations and response formatting
• LaunchDarklyMCPServer: MCP server with stdio transport and tool registration
• Validation: Zod schemas for all inputs
• Auth: Cookie-based session via /internal/account/login + /internal/account/login2

Authentication Flow

1. POST /internal/account/login with email + password
2. PUT /internal/account/login2 with email
3. Session cookies (ldso, pa_ldso, ob_ldso) captured and reused
4. On 401, automatically re-authenticates

License

MIT