Error codes

Error envelope

REST responses carry the envelope as the JSON body with the status below. MCP domain failures return HTTP 200 with the envelope as structuredContent and isError: true. docsUrl links to the code's section on this page, and details never contains credentials.

{
  "error": {
    "code": "validation_failed",
    "message": "The request input is not valid.",
    "hint": "Fix the fields named in details, then send the request again.",
    "retryable": false,
    "details": {
      "fields": [
        {
          "path": "date",
          "message": "Expected a string matching the pattern ^\\d{4}-\\d{2}-\\d{2}$, got \"14/09/2026\""
        }
      ]
    },
    "docsUrl": "https://www.dailygoal.fit/developers/errors#validation_failed"
  }
}

MCP credential failures return HTTP 401 or 403 with the envelope and WWW-Authenticate so the client can authorize. Subscription lapse is a tool error, subscription_required, and does not ask the client to reconnect. Malformed JSON-RPC, unsupported methods and invalid tool names return a JSON-RPC error object instead of this envelope.

The statuses below describe REST responses. For an MCP rate_limited tool error, use the wait in its message; the tool result does not carry a Retry-After header. For unauthorized, check the API token or reconnect the OAuth app if its credential expired or was revoked.

OAuth authorization, registration and token routes use OAuth's error and error_description fields. For example, an invalid client document returns invalid_client (400), a refused refresh returns invalid_grant (400), and paused access returns subscription_required (403). These are separate from the REST and MCP operation envelope below.

Codes