Every tool result carries sources and attribution. The server's instructions ask the assistant to show the attribution notices with the data, and the OpenStreetMap credit with OpenStreetMap fields.

Limits and errors

Each tools/call counts as one call against your key and plan, exactly like a REST call, and is refused the same way (quota_exceeded, endpoint_not_in_plan, rate_limited, live_keys_off).
Discovery, initialize, tools/list and ping are free, but limited to 300 a minute per key.
A refused or failed call comes back as a tool result with isError: true, the message as text and the code in _meta.code, so the assistant can explain it. Unknown tools and malformed requests are JSON-RPC errors.

Authentication

With an API key. Clients that can send a header (Claude Code, Cursor, VS Code, Devin Desktop, the MCP Inspector) send Authorization: Bearer pk_live_... or a test key.

With OAuth. Clients that cannot send a header (ChatGPT, and claude.ai unless your organisation has request headers) connect with OAuth 2.1:

Without credentials, https://www.rallyroam.co.uk/mcp answers 401 with WWW-Authenticate: Bearer resource_metadata="https://www.rallyroam.co.uk/.well-known/oauth-protected-resource/mcp".
The client reads the protected resource metadata and the authorisation server metadata.
It identifies itself with a client ID metadata document (an https client_id), or registers at /oauth/register.
You sign in to your developer account, see which app is asking, choose which of your keys it acts as, and allow it. If you have no developer account yet, create one first: it is free and starts on the sandbox.
The client swaps the code for tokens at /oauth/token (PKCE S256 is required). Access tokens last an hour; refresh tokens last 30 days and change every time they are used.

Tool calls made with the token count against the key you chose. Revoke an app's access at any time from the dashboard, or by revoking the key.

Connecting

Claude: claude.ai, Claude Desktop and Claude Code.
ChatGPT: custom MCP servers, and GPT Actions.
Code editors: Cursor, VS Code with GitHub Copilot, and Devin Desktop (formerly Windsurf).
Other clients: the MCP Inspector, mcp-remote and the raw protocol.

Limits and errors

Authentication

Connecting

Trying it by hand

MCP-server | Udviklercenter