MCP Tasks reference

Each status has a distinct wire contract.

Understand working, input_required, completed, failed and cancelled MCP Tasks payload requirements.

Lifecycle detail

Validate state and sequence.

working carries ordinary task metadata. input_required adds all outstanding inputRequests. completed adds the original method result, even when a tool result has isError true. failed adds a JSON-RPC error. cancelled carries no result or error.

Completed, failed and cancelled are terminal. Once observed, no later snapshot may return the same task to working or input_required.

Continue debugging

Run the lifecycle validator.
Review status-specific payloads.
Check 2025-to-2026 migration.
Test storage, routing, permissions and polling with the official SDK used in production.

MCP Task Trace is independent and is not affiliated with the Model Context Protocol project.