csharp-sdk/samples/TasksExtension

Tasks Extension Sample

Demonstrates the MCP tasks extension (SEP-2663) end-to-end in a single process.

The server is configured with an in-memory IMcpTaskStore, which is sufficient to make any [McpServerTool] method automatically run as a background task when the client opts into the tasks extension on a per-request basis.

The client invokes the same run-report tool two ways:

1. CallToolAsync (auto-poll) — the SDK injects the opt-in marker into _meta, polls tasks/get at the cadence the server suggests, dispatches any input requests through registered handlers, and returns the final CallToolResult (or throws on a terminal Failed/Cancelled).
2. CallToolRawAsync (manual poll) — the caller receives the raw ResultOrCreatedTask<CallToolResult> and drives the lifecycle directly with GetTaskAsync, UpdateTaskAsync, and CancelTaskAsync. Useful when you need to surface progress to a UI or stream task status updates between polls.

Both ends of the conversation are connected in-process over an in-memory Pipe, so no separate server process or HTTP transport is required.

Run

dotnet run --project samples/TasksExtension/TasksExtension.csproj

Expected output:

=== CallToolAsync (auto-poll) ===
  result: report ready

=== CallToolRawAsync (manual poll) ===
  task created: id=… status=Working pollIntervalMs=250
  poll 1: still working …
  …
  task completed after N poll(s): report ready

Notes

• The MCPEXP001 warning is suppressed because the tasks extension is still experimental. The project's <NoWarn> already includes it; if you copy this pattern into your own project, either suppress the diagnostic or wrap the experimental APIs in #pragma warning disable MCPEXP001.
• For production deployments — especially stateless HTTP servers — implement IMcpTaskStore against durable storage and register it as a singleton (see docs/concepts/tasks/tasks.md for the contract).