Developer MCP - Firmable

The developer MCP server lets your AI agent look up companies and people, reveal work emails and phone numbers, and search Firmable data. Calls use your organisation’s developer credits.

Setting	Value
MCP URL	`https://agents.firmable.com/developer/mcp`
Transport	Streamable HTTP
OAuth client ID	Shown on the portal’s Home page with OAuth selected. Replace `<CLIENT_ID>` below with it.
OAuth callback port	`53612`

The portal’s Home page shows these steps for the agent you pick, with your client ID or API key already filled in. Use that if you can.

OAuth or API key

OAuth: your agent opens a browser the first time it connects and you sign in to Firmable. Use this on your own machine.
API key: your agent sends a developer API key with every request. Use this for agents that run without a browser, such as on a server or in CI. Replace <YOUR_FIRMABLE_API_KEY> below with your key.

Firmable only accepts OAuth sign-ins that come back to http://localhost:53612/oauth/callback, and agents can’t register themselves. Always use the client ID and port 53612 exactly as shown. Some agents (Codex, Gemini CLI, Windsurf and opencode) pick a different port for their own sign-in, so their OAuth setup uses mcp-remote, which needs Node.js.

Let your agent set itself up

Paste this into an agent that can run commands, and it reads the steps and installs Firmable itself:

Set up Firmable MCP – https://agents.firmable.com/developer/setup.txt

Claude.ai or Claude Desktop

OAuth
API key

In Claude, open Settings, then Connectors.
Select Add custom connector, name it Firmable and paste the MCP URL.
Under Advanced settings, enter the OAuth Client ID and leave the client secret blank.
Select Add, then Connect, and sign in to Firmable.

In Claude, open Settings, then Connectors.
Select Add custom connector, name it Firmable and paste the MCP URL.
Choose no sign-in, and add a request header named Authorization with the value Bearer <YOUR_FIRMABLE_API_KEY>.
Select Add.

ChatGPT

ChatGPT connects with OAuth only.

In ChatGPT, open Settings, then Apps, then Advanced settings, and turn on Developer mode.
Select Create app, name it Firmable, paste the MCP URL and choose OAuth.
Expand Advanced OAuth settings, set Registration method to User-Defined OAuth Client, enter the Client ID and leave the secret blank.
Select Create, sign in to Firmable and select Allow.

Claude Code

OAuth
API key

Run in your terminal:

claude mcp add --transport http --client-id <CLIENT_ID> --callback-port 53612 firmable https://agents.firmable.com/developer/mcp

Run in your terminal:

claude mcp add --transport http firmable https://agents.firmable.com/developer/mcp --header "Authorization: Bearer <YOUR_FIRMABLE_API_KEY>"

Cursor

OAuth
API key

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "firmable": {
      "url": "https://agents.firmable.com/developer/mcp",
      "auth": {
        "CLIENT_ID": "<CLIENT_ID>"
      }
    }
  }
}

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "firmable": {
      "url": "https://agents.firmable.com/developer/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_FIRMABLE_API_KEY>"
      }
    }
  }
}

VS Code

OAuth
API key

Add to .vscode/mcp.json:

{
  "servers": {
    "firmable": {
      "type": "http",
      "url": "https://agents.firmable.com/developer/mcp",
      "oauth": {
        "clientId": "<CLIENT_ID>"
      }
    }
  }
}

Add to .vscode/mcp.json:

{
  "servers": {
    "firmable": {
      "type": "http",
      "url": "https://agents.firmable.com/developer/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_FIRMABLE_API_KEY>"
      }
    }
  }
}

Codex

OAuth
API key

Run in your terminal:

codex mcp add firmable -- npx -y mcp-remote https://agents.firmable.com/developer/mcp 53612 --host localhost --static-oauth-client-info '{"client_id":"<CLIENT_ID>"}'

Run in your terminal:

export FIRMABLE_API_KEY="<YOUR_FIRMABLE_API_KEY>"
codex mcp add firmable --url https://agents.firmable.com/developer/mcp --bearer-token-env-var FIRMABLE_API_KEY

Windsurf

OAuth
API key

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "firmable": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://agents.firmable.com/developer/mcp",
        "53612",
        "--host",
        "localhost",
        "--static-oauth-client-info",
        "{\"client_id\":\"<CLIENT_ID>\"}"
      ]
    }
  }
}

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "firmable": {
      "serverUrl": "https://agents.firmable.com/developer/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_FIRMABLE_API_KEY>"
      }
    }
  }
}

Gemini CLI

OAuth
API key

Add to ~/.gemini/settings.json:

{
  "mcpServers": {
    "firmable": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://agents.firmable.com/developer/mcp",
        "53612",
        "--host",
        "localhost",
        "--static-oauth-client-info",
        "{\"client_id\":\"<CLIENT_ID>\"}"
      ]
    }
  }
}

Run in your terminal:

gemini mcp add --transport http firmable https://agents.firmable.com/developer/mcp --header "Authorization: Bearer <YOUR_FIRMABLE_API_KEY>"

opencode

OAuth
API key

Add to opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "firmable": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "mcp-remote",
        "https://agents.firmable.com/developer/mcp",
        "53612",
        "--host",
        "localhost",
        "--static-oauth-client-info",
        "{\"client_id\":\"<CLIENT_ID>\"}"
      ],
      "enabled": true
    }
  }
}

Add to opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "firmable": {
      "type": "remote",
      "url": "https://agents.firmable.com/developer/mcp",
      "enabled": true,
      "headers": {
        "Authorization": "Bearer <YOUR_FIRMABLE_API_KEY>"
      }
    }
  }
}

Other MCP clients

OAuth
API key

Add to mcp.json:

{
  "mcpServers": {
    "firmable": {
      "type": "http",
      "url": "https://agents.firmable.com/developer/mcp",
      "oauth": {
        "clientId": "<CLIENT_ID>"
      }
    }
  }
}

Add to mcp.json:

{
  "mcpServers": {
    "firmable": {
      "type": "http",
      "url": "https://agents.firmable.com/developer/mcp",
      "headers": {
        "Authorization": "Bearer <YOUR_FIRMABLE_API_KEY>"
      }
    }
  }
}

Check it works

Ask your agent: “Use Firmable to look up the company at firmable.com.” If it can’t find the Firmable tools, restart the agent. If sign-in fails, check you used the client ID and port 53612 exactly as shown.

​OAuth or API key

​Let your agent set itself up

​Claude.ai or Claude Desktop

​ChatGPT

​Claude Code

​Cursor

​VS Code

​Codex

​Windsurf

​Gemini CLI

​opencode

​Other MCP clients

​Check it works

OAuth or API key

Let your agent set itself up

Claude.ai or Claude Desktop

ChatGPT

Claude Code

Cursor

VS Code

Codex

Windsurf

Gemini CLI

opencode

Other MCP clients

Check it works