Python: MCP long-running task support in Python by peibekwe · Pull Request #6319 · microsoft/agent-framework · GitHub

Motivation and Context

Ports the MCP long-running task (SEP-2663) feature from .NET to Python. When an MCP server advertises a tool with execution.taskSupport == "required", MCPTool now transparently drives the tools/call - tasks/get (polled) - tasks/result lifecycle, so the agent's function-calling loop sees a normal synchronous tool result.

This is purely additive, those tools could not complete via plain tools/call before, so the new path fixes a previously broken case without changing any existing behavior. Matches The work done in #5994

Fixes #6258

Contribution Checklist

The code builds clean without any errors or warnings
The PR follows the Contribution Guidelines
All unit tests pass, and I have added new tests where possible
Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

Pull request overview

Adds Python-side support for MCP SEP-2663 long-running tasks so tools advertising execution.taskSupport == "required" are executed via the tools/call → tasks/get (poll) → tasks/result lifecycle while still presenting a normal synchronous tool result to the agent loop.

Changes:

Implement MCP long-running task orchestration in MCPTool.call_tool (task-aware routing, polling, result coercion, cancellation, reconnect behavior, and legacy fallbacks).
Add extensive unit coverage for required/optional routing, TTL propagation, polling interval clamping, cancellation behavior, reconnect semantics, and legacy/fallback server responses.
Document and sample the feature (new sample script + README updates + core AGENTS.md update) and export MCPTaskOptions as a public API.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
python/samples/02-agents/mcp/README.md	Adds the new long-running task sample and documents additional prerequisites for it.
python/samples/02-agents/mcp/mcp_long_running_task.py	New end-to-end sample that self-spawns a stdio MCP server advertising taskSupport=required and exercises transparent task handling.
python/packages/core/tests/core/test_mcp.py	New test region covering the SEP-2663 lifecycle, fallbacks, reconnect/cancellation behavior, and option validation.
python/packages/core/AGENTS.md	Documents the MCP task feature and usage/behavior at a high level (one bullet needs to be corrected to match implementation).
python/packages/core/agent_framework/_mcp.py	Core implementation: MCPTaskOptions, task-support discovery from list_tools, task-aware call_tool routing, and the tasks/* lifecycle driver.
python/packages/core/agent_framework/_feature_stage.py	Adds the MCP_LONG_RUNNING_TASKS experimental feature flag identifier.
python/packages/core/agent_framework/init.py	Exports MCPTaskOptions from the public package surface.

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework
_feature_stage.py	168	10	94%	109, 155, 210, 221, 241, 279, 290, 296, 327, 355
_mcp.py	1046	88	91%	230, 249, 404, 464–465, 594, 656, 669, 693–694, 713–716, 718–719, 723, 749, 782–784, 786, 839–841, 896–897, 1080, 1121–1122, 1135, 1138, 1146–1147, 1152–1153, 1159, 1207–1208, 1223–1224, 1232–1233, 1238–1239, 1245, 1309, 1312, 1339, 1362–1366, 1389–1391, 1396, 1400–1401, 1485, 1494, 1500, 1561, 1576–1577, 1584–1585, 1590–1591, 1596, 1600, 1617, 1679, 1868, 1870, 1892, 1894–1897, 1910–1911, 1958, 2010–2011, 2014, 2500
TOTAL	38273	4447	88%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
7630	34 💤	0 ❌	0 🔥	2m 1s ⏱️

Automated Code Review

Reviewers: 4 | Confidence: 88% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Design Approach

Automated review by peibekwe's agents

- pyupgrade: drop forward-reference string annotations in _mcp.py (Python 3.10+ resolves them natively now that MCPTaskOptions is defined before use). - AGENTS.md: align reconnect description with current behavior. Phase 1 (initial tools/call) does NOT retry on connection loss; raises 'connection lost; task state unknown' instead, so a server that accepted the request but lost the response cannot start the operation twice. Phase 2 (tasks/get / tasks/result) still reconnects once against the same task_id. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Automated Code Review

Reviewers: 3 | Confidence: 85% | Result: All clear

Reviewed: Security Reliability, Test Coverage, Design Approach

Automated review by peibekwe's agents

MCP long-running task support in Python

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Peter Ibekwe (peibekwe) self-assigned this Jun 4, 2026

Copilot AI review requested due to automatic review settings June 4, 2026 00:24

Copilot started reviewing on behalf of Peter Ibekwe (peibekwe) June 4, 2026 00:24 View session

Evan Mattson (moonbox3) added documentation Usage: [Issues, PRs], Target: documentation in the code base and learn docs python Usage: [Issues, PRs], Target: Python labels Jun 4, 2026

github-actions Bot changed the title MCP long-running task support in Python Python: MCP long-running task support in Python Jun 4, 2026

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Peter Ibekwe (peibekwe) and others added 3 commits June 3, 2026 17:34

Merge branch 'main' into peibekwe/mcp-lro-python

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Fix bandit nosec marker for CI pipeline

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Peter Ibekwe (peibekwe) marked this pull request as ready for review June 4, 2026 00:52

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Evan Mattson (moonbox3) reviewed Jun 4, 2026

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Address PR feedbacks

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Clarifiied comments and addressed more PR feedbacks.

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Tao Chen (TaoChenOSU) approved these changes Jun 4, 2026

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Evan Mattson (moonbox3) approved these changes Jun 5, 2026

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Peter Ibekwe (peibekwe) added this pull request to the merge queue Jun 5, 2026

Merged via the queue into main with commit bf4ad48 Jun 5, 2026
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Copilot AI mentioned this pull request Jun 9, 2026

Python: bump package versions for 1.8.1 release #6420

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Vincent Biret (baywet) deleted the peibekwe/mcp-lro-python branch September 17, 2026 14:54

Python: MCP long-running task support in Python by peibekwe · Pull Request #6319 · microsoft/agent-framework · GitHub

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Python: MCP long-running task support in Python - #6319

Python: MCP long-running task support in Python#6319
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Python: MCP long-running task support in Python by peibekwe · Pull Request #6319 · microsoft/agent-framework · GitHub

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Python: MCP long-running task support in Python - #6319

Python: MCP long-running task support in Python#6319Peter Ibekwe (peibekwe) merged 6 commits intomainmicrosoft/agent-framework:mainfrom peibekwe/mcp-lro-pythonmicrosoft/agent-framework:peibekwe/mcp-lro-pythonCopy head branch name to clipboard

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