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Implement SEP-1686: Tasks #1546

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#1645
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Implement SEP-1686: Tasks#1546
#1645
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maxisbey
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enhancementRequest for a new feature that's not currently supported

Description

@felixweinberger
felixweinberger
opened on Oct 30, 2025

This is a tracking issue for implementation of SEP-1686.

Summary

This SEP introduces a general-purpose Tasks capability for managing long-running operations in MCP, generalizing task management to all JSON-RPC requests. The Python SDK needs to implement support for servers to initiate operations and return immediately with task identifiers, enable clients to check back periodically for results or subscribe to task completion notifications, handle disconnections and reconnections gracefully, and provide APIs for managing multiple concurrent long-running tasks across all MCP operations to enable more resilient handling of asynchronous operations.

Related Issues & PRs

  • Implementation PRs: n/a
  • Related PRs: #1398
  • Related Issues: #769

Activity

  1. felixweinberger
    added this to 2025-11-25 Implementationon Oct 30, 2025
  2. felixweinberger
    moved this to In review in 2025-11-25 Implementationon Oct 30, 2025
  3. felixweinberger
    added
    pending SEP approvalWhen a PR is attached as an implementation detail to a SEP, we mark it as such for triage.
    enhancement
    on Oct 30, 2025
  4. felixweinberger
    self-assigned this
    on Oct 30, 2025
  5. felixweinberger
    added
    enhancementRequest for a new feature that's not currently supported
    and removed
    enhancement deprecated
    on Nov 12, 2025
  6. felixweinberger
    removed their assignment
    on Nov 13, 2025
  7. felixweinberger
    moved this from In review to Ready in 2025-11-25 Implementationon Nov 20, 2025
  8. felixweinberger
    linked a pull request that will close this issueSEP-1686: Tasks #1645on Nov 20, 2025
  9. felixweinberger
    linked a pull request that will close this issueSEP-1686: Tasks #1554on Nov 20, 2025
  10. felixweinberger
    assigned
    maxisbey
    on Nov 20, 2025

  11. felixweinberger commented on Nov 20, 2025

    @felixweinberger
    felixweinberger
    on Nov 20, 2025
    ContributorAuthor

    Hi @LucaButBoring looks like you have a Draft PR for this you're planning to update?

    Mind if I assign this one to you?

  12. felixweinberger
    moved this from Ready to In progress in 2025-11-25 Implementationon Nov 20, 2025
  13. felixweinberger
    unassigned
    maxisbey
    on Nov 20, 2025
  14. felixweinberger
    removed a link to a pull requestSEP-1686: Tasks #1645on Nov 20, 2025
  15. felixweinberger
    assigned
    maxisbey
    on Nov 20, 2025

  16. LucaButBoring commented on Nov 21, 2025

    @LucaButBoring
    LucaButBoring
    on Nov 21, 2025
    Contributor

    Relaying here from #general-sdk-dev:

    There doesn't seem to be a central ticket for all SDK implementations of a particular change, so sharing this here for SEP-1686 -- the following revisions have been merged on top of the base specification PR for tasks:

    • Clarify request lifetimes in task diagrams: PR
    • Fix capability phrasing in spec: PR
    • Remove an incorrectly-added field from notifications/cancelled: PR
    • Adjust schema to better-communicate where tasks are valid: PR
    • Rename/move annotations.taskHint to execution.taskSupport, tweak its enum values, and change a SHOULD to a MUST for the behavior when this is declared:
    • GetTask polling clarification: PR
    • SSE stream management clarification: PR

    The actual functional changes should be limited to taskHint, but the rest should help clarify some details around polling.

    To save the trouble of going through each of the above PRs one by one, you can also go to the file on the "Files changed" tab here, searching for docs/specification/draft/basic/utilities/tasks.mdx, and then using the "Display the rich diff" button, as shown:
    Image

  17. LucaButBoring commented on Nov 24, 2025

    @LucaButBoring
    LucaButBoring
    on Nov 24, 2025
    Contributor

    One very last change (we're doing a hard cutoff on additional changes here): adding a lastUpdatedAt to the Task object: modelcontextprotocol/modelcontextprotocol#1875

  18. felixweinberger
    linked a pull request that will close this issueSEP-1686: Tasks #1645on Nov 25, 2025
  19. maxisbey
    closed this as completedin #1645on Nov 28, 2025
  20. github-project-automation
    moved this from In progress to Done in 2025-11-25 Implementationon Nov 28, 2025
  21. felixweinberger
    removed
    pending SEP approvalWhen a PR is attached as an implementation detail to a SEP, we mark it as such for triage.
    on Dec 1, 2025

  22. jief123 commented on Feb 28, 2026

    @jief123
    jief123
    on Feb 28, 2026

    The Tasks implementation from #1645 is solid, but I found a spec compliance gap: the high-level API (MCPServer.add_tool(), ToolManager.add_tool(), Tool.from_function()) doesn't expose the execution parameter, so there's no way to declare execution.taskSupport per tool.

    Per the MCP spec (2025-11-25), tools must declare task support via execution.taskSupport in tools/list. Without this, tools default to taskSupport: "forbidden" even when enable_tasks() is called — clients like MCP Inspector won't show the "Run as task" option.

    Details in #2156, fix in #2157.

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