Mirror of https://github.com/modelcontextprotocol/ext-tasks — This repository provides a reference for the tasks extensions to the MCP protocol, allowing for long-running operations, such as Agent communication, in MCP.
- TypeScript 100%
| Filename | Latest commit message | Latest commit date |
|---|---|---|
e4345978beThe generated JSON Schema artifact previously failed to encode several
normative requirements, forcing non-TypeScript implementations to
maintain their own mirrors of core shapes and discriminators:
- InputRequest/InputResponse collapsed to anyOf:[{},{},{}] because the
imported request/result types resolved to empty schemas, accepting
any instance.
- The required resultType discriminators ('task' on CreateTaskResult,
'complete' on Get/Update/CancelTaskResult) appeared nowhere in the
artifact despite being normative MUSTs in the extension prose.
- Strip-mode object emission produced additionalProperties:false inside
allOf intersections, making CreateTaskResult unsatisfiable: every
spec-conformant instance (with resultType or _meta) was rejected.
The canonical specification is now the sole source of truth for all
core-spec shapes — no SDK package is consulted at any layer.
scripts/fetch-spec-schema.ts vendors spec.schema.json and spec.types.ts
from the same recorded spec commit with provenance headers:
- schema.ts imports every core type (JSON-RPC envelopes, Result,
NotificationParams, the MRTR InputRequests/InputResponses, and the
JSON-RPC Error object) from the vendored spec.types.ts, deleting the
local mirrors that had already drifted from upstream.
- generate-schemas.ts emits $ref for all spec-owned types — including
the JSON-RPC envelopes intersected by the extension's own types — and
splices their transitive $ref closure verbatim from the vendored
canonical schema.json. Core-spec corrections flow in via an explicit,
reviewable refresh (npm run fetch:spec-schema) instead of silently
diverging. The @modelcontextprotocol/sdk devDependency is removed.
- Runtime Zod stand-ins for imported types are permissive locals whose
shapes never reach the artifact; generation fails on any unmapped
placeholder, and on any definition that cannot be converted.
- JSON Schema emission uses io:'input' so TypeScript's open interface
semantics are preserved and intersections remain satisfiable.
- resultType discriminators are encoded structurally in schema.ts.
- FailedTask.error now requires the canonical JSON-RPC Error shape;
ttlMs and pollIntervalMs are integers per the prose.
- createdAt/lastUpdatedAt deliberately remain unconstrained strings:
the prose requires ISO 8601 generally, and JSON Schema's date-time
format/pattern machinery can only express RFC 3339, which would
reject valid basic-form timestamps.
Validated with a Draft 2020-12 jsonschema matrix covering union
rejection/acceptance, discriminator enforcement, JSON-RPC envelope
enforcement, error-shape and integer constraints, byte-fidelity of all
56 spliced canonical definitions, complete $ref resolution, and
check-mode idempotency.
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| .github/workflows | ||
| .vitepress | ||
| public | ||
| schema/draft | ||
| scripts | ||
| seps | ||
| specification/draft | ||
| .gitignore | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| index.md | ||
| LICENSE | ||
| MAINTAINERS.md | ||
| package-lock.json | ||
| package.json | ||
| README.md | ||
| SECURITY.md | ||
| tsconfig.json | ||
MCP Tasks Extension
This repository contains the official Model Context Protocol Tasks extension (io.modelcontextprotocol/tasks), based on SEP-2663.
Overview
This extension defines the Tasks primitive for the Model Context Protocol (MCP). Tasks are durable state machines that carry information about the underlying execution state of a request, enabling requestor polling and deferred result retrieval. Each task is uniquely identifiable by a receiver-generated task ID.
Tasks are useful for:
- Representing expensive computations and batch processing requests
- Integrating seamlessly with external job/workflow APIs
- Enabling call-now, fetch-later execution patterns
Extension Identifier: io.modelcontextprotocol/tasks
Development
Schema Generation
The JSON Schema is auto-generated from the TypeScript type definitions using ts-to-zod and Zod's toJSONSchema(). Do not hand-edit schema.json or generated/schema.ts.
# Generate Zod schemas and JSON Schema from schema.ts
npm run generate:schemas
# Verify TypeScript compiles and generated files are up to date
npm run check:schema
Governance
This repository follows the Model Context Protocol Governance process. See MAINTAINERS.md for the list of maintainers specific to this repository.
Policies
This repository follows the Model Context Protocol project policies:
License
This project is licensed under the Apache License 2.0. See LICENSE for details.