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Common REST statuses

  • 400 for malformed pagination cursors (INVALID_CURSOR)
  • 401 for missing or invalid credentials
  • 403 for keys that do not have access to the requested operation
  • missing or inaccessible stats IDs are reported in response metadata rather than as 404
  • 422 for validation failures (VALIDATION_ERROR), including invalid parameter combinations such as passing both cursor and since to the partner feed
  • 429 for rate limiting
Each API key has a request allowance. The default is 1000 requests, replenished in full one hour after the previous replenishment. Exhausting the allowance returns 429 with code RATE_LIMITED and, when available, a Retry-After header. Production limits vary by account or environment.

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Common MCP failures

  • missing MCP credentials
  • invalid OAuth access token or audience mismatch
  • OAuth token without a supported Centaur MCP scope
  • invalid tool arguments
  • exhausted MCP usage quota
MCP OAuth failures include WWW-Authenticate metadata pointing to the protected resource metadata URL. Scope failures can include insufficient_scope; invalid or wrong-audience tokens can include invalid_token. MCP has one usage quota per Centaur user across every connected client. The default is 1000 admitted operations per hour. Eligible paid partners receive their Partner Tier quota, initially 10000 operations per hour. A schema-valid tools/call or resources/read consumes one operation before execution. Discovery, listing, authentication failures, validation failures, and quota rejections do not consume usage. Tool quota failures use isError: true and include stable details under io.centaur/mcp-quota. Resource quota failures use the equivalent JSON-RPC error. Both include the reset time when available.

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Operational guidance

  • Log and preserve requestId from REST failures when asking for support.
  • Prefer explicit time bounds and limits when an agent is exploring large result sets.
  • If a response is narrower than expected, check the echoed applied bounds and remember that some rows can be silently suppressed by access or eligibility rules.
  • Use the generated API reference for endpoint-specific error examples and response schemas.
Last modified on September 11, 2026