Visitar URL original
mcpkit/examples/tasks-v2 at main · panyam/mcpkit · GitHub
Skip to content

tasks-v2

Directory actions

More options

Directory actions

More options

Latest commit

 

History

History

tasks-v2

Folders and files

NameName
Last commit message
Last commit date

parent directory

..
Makefile
Makefile
 
 
README.md
README.md
 
 
WALKTHROUGH.md
WALKTHROUGH.md
 
 
go.mod
go.mod
 
 
go.sum
go.sum
 
 
justfile
justfile
 
 
main.go
main.go
 
 
walkthrough.go
walkthrough.go
 
 

README.md

MCP Tasks v2 (SEP-2663), Server-Directed Async + MRTR

Stable - implements SEP-2663 (Tasks v2), merged into the MCP spec.

Server-side implementation of the v2 Tasks extension. v2 inverts v1's client-driven model: the server decides when to create a task, and clients call tools/call normally with no task hint.

🚀 Skip to the guided walkthrough → - 8-step demokit walkthrough covering the full v2 surface: extension negotiation, polymorphic tools/call, inlined results, the new tasks/update MRTR loop, ack-only cancel, and tool-vs-protocol error semantics. Run it with just serve + just demo.

🔁 Migrating from v1? See the v1 → v2 migration guide for the wire-shape diff, server entry points (tasks.Register in ext/tasks / server.RegisterTasksV1), and the rolling-upgrade recipe.

Key Differences from v1

Aspect v1 (SEP-1686, core 2025-11-25) v2 (SEP-2663, Final ext)
Capability slot capabilities.tasks capabilities.extensions["io.modelcontextprotocol/tasks"]
Client opt-in (none) client.WithTasksExtension() required
Client task hint task: {ttl, pollInterval} in params none - server decides
Discriminator on tools/call absent (use taskId presence) resultType: "task"
Read endpoints tasks/get + tasks/result (two RTTs) tasks/get only (result inlined)
Result on terminal tasks/get only status - fetch separately inlined result / error / inputRequests
MRTR resume path side-channel via tasks/result long-poll tasks/update (new method)
tasks/cancel response rich task envelope empty {} ack
TTL field ttl (ms by convention) ttlMs (integer milliseconds)
Poll-interval field pollInterval pollIntervalMs (integer milliseconds)
Tool errors status: failed status: completed, result.isError: true
Protocol errors status: failed, error: ... status: failed, error: {code, message, data}
tasks/list exists removed
Mcp-Name HTTP header not set set on task-creating responses (SEP-2243)

Quick Start

just serve   # terminal 1: v2 tasks server on :8080
just demo     # terminal 2: demokit walkthrough (7 steps)

See WALKTHROUGH.md for the full step-by-step description and sequence diagram.

Agent mode

Moved. An agent driving these task tools is now demonstrated in chakra, the agent SDK, which was extracted from mcpkit into its own repository. The point it made still holds and is covered there by host/tasks_test.go and the agent-async example: a model calls a sync-only tool and a server-directed async tool the same way, and the SEP-2663 task machinery never surfaces to it.

This example stays focused on the server side.

What it demonstrates

  • Tasks-as-extension negotiation. client.WithTasksExtension() opts in during initialize; servers gate task-creating tools/call and every tasks/* method on it.
  • Polymorphic tools/call with the resultType: "task" discriminator, so the server decides whether to create a task, no client hint required.
  • Inlined results on terminal tasks/get, where result / error / inputRequests arrive in one RTT, tasks/result removed.
  • Tool-vs-protocol error semantics: tool errors land in status: completed, isError: true; protocol errors in status: failed with structured error.
  • Empty-ack tasks/cancel plus follow-up tasks/get to observe the resulting cancelled status.
  • The new tasks/update MRTR resume path closing the elicitation/sampling loop.
  • The Mcp-Name HTTP response header (SEP-2243) carrying taskIds for observability without parsing the body.
  • TaskCallbacks proxy pattern (external task store) via external_job.

Tools

Tool TaskSupport What it demonstrates
greet forbidden Sync-only - server returns ToolResult directly, no resultType
slow_compute optional Server creates a task; client gets resultType: "task" discriminator
failing_job required Tool error path → terminal completed + isError: true
protocol_error_job required Protocol error path → terminal failed + error: {...}
external_job required TaskCallbacks proxy pattern (external task store)

Conformance

Where to look in the code

Next steps