Python: migrate mcp connector to mcp 2.x by ProgrammerPlus1998 · Pull Request #14251 · microsoft/semantic-kernel

ProgrammerPlus1998 · 2026-08-03T11:09:35Z

Motivation and Context

The mcp dependency is pinned to mcp>=1.26.0,<2.0, which blocks the MCP Python SDK 2.x line. 2.0 introduced several breaking changes that the connector relies on, so the integration and its tests need to be updated before the pin can be loosened.

Fixes #14246

This takes the "upgrade to 2.x" approach (require the 2.x SDK) rather than trying to support both 1.x and 2.x at once.

Description

Updates the MCP connector (python/semantic_kernel/connectors/mcp.py) to the 2.0 API and bumps the pin to mcp>=2.0.0,<3.0 (both the main dependency and the mcp extra). uv.lock regenerated.

Server side (create_mcp_server_from_kernel / create_mcp_server_from_functions):

The lowlevel @server.list_tools() / call_tool() / get_prompt() / list_prompts() / set_logging_level() decorators were removed. Handlers are now passed to the Server(...) constructor (on_list_tools, on_call_tool, on_list_prompts, on_get_prompt, on_set_logging_level), receive a (ServerRequestContext, params) pair, and return result models (ListToolsResult, CallToolResult, GetPromptResult, EmptyResult).
The per-request session used to emit log messages now comes from the handler's ServerRequestContext (the removed server.request_context no longer exists).

Client side (MCP*Plugin):

streamablehttp_client → streamable_http_client; it now yields a 2-tuple and no longer accepts headers/timeout/sse_read_timeout, so MCPStreamableHttpPlugin builds an httpx2 client via create_mcp_http_client when those are set.
ClientSession(read_timeout_seconds=...) now takes float seconds instead of a timedelta.
Sampling callback context: mcp.shared.context.RequestContext → mcp.client.session.ClientRequestContext.
message_handler now receives ServerNotification | Exception (no more RequestResponder); list-changed notifications are matched via .method directly.
Session re-init check uses session.initialize_result instead of the removed _request_id.
McpError → MCPError (raised with code=/message=).
camelCase model fields → snake_case throughout: input_schema, mime_type, tool_use_id, model_preferences, max_tokens, system_prompt.

Removed in 2.0:

The websocket transport (mcp.client.websocket) no longer exists, so MCPWebsocketPlugin.get_mcp_client() now raises a clear KernelPluginInvalidConfigurationError at connect time instead of failing at import. (Happy to drop the class entirely if preferred.)

Tests / assets:

tests/assets/test_plugins/TestMCPPlugin/mcp_server.py: FastMCP → MCPServer.
tests/unit/connectors/mcp/test_mcp.py: updated fixtures/mocks for the 2.0 shapes (input_schema, streamable_http_client 2-tuple, initialize_result), rewrote the server-handler assertions to the new get_request_handler(method) API, and replaced the websocket test with one asserting the removal error.

Contribution Checklist

The code builds clean without any errors or warnings (ruff check + ruff format clean, mypy clean on the connector)
The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
All unit tests pass, and I have added new tests where possible — 23 passed (unit), 1 passed (integration, real stdio MCP server) under mcp 2.0.0
I didn't break anyone 😄

Bump the mcp dependency to >=2.0.0,<3.0 and update the connector for the 2.0 breaking changes: - Server: the lowlevel @server.list_tools()/call_tool()/get_prompt()/ set_logging_level() decorators were removed. Handlers are now passed to the Server(...) constructor as on_list_tools/on_call_tool/on_list_prompts/ on_get_prompt/on_set_logging_level, take a (ServerRequestContext, params) pair, and return result models (ListToolsResult/CallToolResult/...). The per-request session for sending log messages is taken from the handler context instead of the removed server.request_context. - Client: streamablehttp_client -> streamable_http_client (2-tuple); its headers/timeout/sse_read_timeout kwargs were removed, so the streamable http plugin builds an httpx2 client via create_mcp_http_client instead. ClientSession.read_timeout_seconds now takes float seconds. - camelCase model fields are snake_case: input_schema, mime_type, tool_use_id, model_preferences, max_tokens, system_prompt. - RequestContext -> ClientRequestContext for the sampling callback; message_handler now receives ServerNotification|Exception (no RequestResponder), and list-changed notifications are matched via .method directly. - McpError -> MCPError (raised with code/message). - The websocket transport was removed in mcp 2.0; MCPWebsocketPlugin now raises a clear configuration error at connect time instead of failing at import. - Tests and the test MCP server asset updated; uv.lock regenerated. Tests: 23 passed (unit), 1 passed (integration, real stdio server). ruff and mypy clean.

microsoft-github-policy-service · 2026-08-03T11:09:49Z

@ProgrammerPlus1998 please read the following Contributor License Agreement(CLA). If you agree with the CLA, please reply with the following information.

@microsoft-github-policy-service agree [company="{your company}"]

Options:

(default - no company specified) I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.
@microsoft-github-policy-service agree
(when company given) I am making Submissions in the course of work for my employer (or my employer has intellectual property rights in my Submissions by contract or applicable law). I have permission from my employer to make Submissions and enter into this Agreement on behalf of my employer. By signing below, the defined term “You” includes me and my employer.
@microsoft-github-policy-service agree company="Microsoft"

Contributor License Agreement

Contribution License Agreement

This Contribution License Agreement (“Agreement”) is agreed to by the party signing below (“You”),
and conveys certain license rights to Microsoft Corporation and its affiliates (“Microsoft”) for Your
contributions to Microsoft open source projects. This Agreement is effective as of the latest signature
date below.

Definitions.
“Code” means the computer software code, whether in human-readable or machine-executable form,
that is delivered by You to Microsoft under this Agreement.
“Project” means any of the projects owned or managed by Microsoft and offered under a license
approved by the Open Source Initiative (www.opensource.org).
“Submit” is the act of uploading, submitting, transmitting, or distributing code or other content to any
Project, including but not limited to communication on electronic mailing lists, source code control
systems, and issue tracking systems that are managed by, or on behalf of, the Project for the purpose of
discussing and improving that Project, but excluding communication that is conspicuously marked or
otherwise designated in writing by You as “Not a Submission.”
“Submission” means the Code and any other copyrightable material Submitted by You, including any
associated comments and documentation.
Your Submission. You must agree to the terms of this Agreement before making a Submission to any
Project. This Agreement covers any and all Submissions that You, now or in the future (except as
described in Section 4 below), Submit to any Project.
Originality of Work. You represent that each of Your Submissions is entirely Your original work.
Should You wish to Submit materials that are not Your original work, You may Submit them separately
to the Project if You (a) retain all copyright and license information that was in the materials as You
received them, (b) in the description accompanying Your Submission, include the phrase “Submission
containing materials of a third party:” followed by the names of the third party and any licenses or other
restrictions of which You are aware, and (c) follow any other instructions in the Project’s written
guidelines concerning Submissions.
Your Employer. References to “employer” in this Agreement include Your employer or anyone else
for whom You are acting in making Your Submission, e.g. as a contractor, vendor, or agent. If Your
Submission is made in the course of Your work for an employer or Your employer has intellectual
property rights in Your Submission by contract or applicable law, You must secure permission from Your
employer to make the Submission before signing this Agreement. In that case, the term “You” in this
Agreement will refer to You and the employer collectively. If You change employers in the future and
desire to Submit additional Submissions for the new employer, then You agree to sign a new Agreement
and secure permission from the new employer before Submitting those Submissions.
Licenses.

Copyright License. You grant Microsoft, and those who receive the Submission directly or
indirectly from Microsoft, a perpetual, worldwide, non-exclusive, royalty-free, irrevocable license in the
Submission to reproduce, prepare derivative works of, publicly display, publicly perform, and distribute
the Submission and such derivative works, and to sublicense any or all of the foregoing rights to third
parties.
Patent License. You grant Microsoft, and those who receive the Submission directly or
indirectly from Microsoft, a perpetual, worldwide, non-exclusive, royalty-free, irrevocable license under
Your patent claims that are necessarily infringed by the Submission or the combination of the
Submission with the Project to which it was Submitted to make, have made, use, offer to sell, sell and
import or otherwise dispose of the Submission alone or with the Project.
Other Rights Reserved. Each party reserves all rights not expressly granted in this Agreement.
No additional licenses or rights whatsoever (including, without limitation, any implied licenses) are
granted by implication, exhaustion, estoppel or otherwise.

Representations and Warranties. You represent that You are legally entitled to grant the above
licenses. You represent that each of Your Submissions is entirely Your original work (except as You may
have disclosed under Section 3). You represent that You have secured permission from Your employer to
make the Submission in cases where Your Submission is made in the course of Your work for Your
employer or Your employer has intellectual property rights in Your Submission by contract or applicable
law. If You are signing this Agreement on behalf of Your employer, You represent and warrant that You
have the necessary authority to bind the listed employer to the obligations contained in this Agreement.
You are not expected to provide support for Your Submission, unless You choose to do so. UNLESS
REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING, AND EXCEPT FOR THE WARRANTIES
EXPRESSLY STATED IN SECTIONS 3, 4, AND 6, THE SUBMISSION PROVIDED UNDER THIS AGREEMENT IS
PROVIDED WITHOUT WARRANTY OF ANY KIND, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY OF
NONINFRINGEMENT, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE.
Notice to Microsoft. You agree to notify Microsoft in writing of any facts or circumstances of which
You later become aware that would make Your representations in this Agreement inaccurate in any
respect.
Information about Submissions. You agree that contributions to Projects and information about
contributions may be maintained indefinitely and disclosed publicly, including Your name and other
information that You submit with Your Submission.
Governing Law/Jurisdiction. This Agreement is governed by the laws of the State of Washington, and
the parties consent to exclusive jurisdiction and venue in the federal courts sitting in King County,
Washington, unless no federal subject matter jurisdiction exists, in which case the parties consent to
exclusive jurisdiction and venue in the Superior Court of King County, Washington. The parties waive all
defenses of lack of personal jurisdiction and forum non-conveniens.
Entire Agreement/Assignment. This Agreement is the entire agreement between the parties, and
supersedes any and all prior agreements, understandings or communications, written or oral, between
the parties relating to the subject matter hereof. This Agreement may be assigned by Microsoft.

microsoft-github-policy-service · 2026-08-03T11:09:50Z

@ProgrammerPlus1998 please read the following Contributor License Agreement(CLA). If you agree with the CLA, please reply with the following information.

@microsoft-github-policy-service agree [company="{your company}"]

Options:

(default - no company specified) I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.
@microsoft-github-policy-service agree
(when company given) I am making Submissions in the course of work for my employer (or my employer has intellectual property rights in my Submissions by contract or applicable law). I have permission from my employer to make Submissions and enter into this Agreement on behalf of my employer. By signing below, the defined term “You” includes me and my employer.
@microsoft-github-policy-service agree company="Microsoft"

Contributor License Agreement

Contribution License Agreement

This Contribution License Agreement (“Agreement”) is agreed to by the party signing below (“You”),
and conveys certain license rights to Microsoft Corporation and its affiliates (“Microsoft”) for Your
contributions to Microsoft open source projects. This Agreement is effective as of the latest signature
date below.

Definitions.
“Code” means the computer software code, whether in human-readable or machine-executable form,
that is delivered by You to Microsoft under this Agreement.
“Project” means any of the projects owned or managed by Microsoft and offered under a license
approved by the Open Source Initiative (www.opensource.org).
“Submit” is the act of uploading, submitting, transmitting, or distributing code or other content to any
Project, including but not limited to communication on electronic mailing lists, source code control
systems, and issue tracking systems that are managed by, or on behalf of, the Project for the purpose of
discussing and improving that Project, but excluding communication that is conspicuously marked or
otherwise designated in writing by You as “Not a Submission.”
“Submission” means the Code and any other copyrightable material Submitted by You, including any
associated comments and documentation.
Your Submission. You must agree to the terms of this Agreement before making a Submission to any
Project. This Agreement covers any and all Submissions that You, now or in the future (except as
described in Section 4 below), Submit to any Project.
Originality of Work. You represent that each of Your Submissions is entirely Your original work.
Should You wish to Submit materials that are not Your original work, You may Submit them separately
to the Project if You (a) retain all copyright and license information that was in the materials as You
received them, (b) in the description accompanying Your Submission, include the phrase “Submission
containing materials of a third party:” followed by the names of the third party and any licenses or other
restrictions of which You are aware, and (c) follow any other instructions in the Project’s written
guidelines concerning Submissions.
Your Employer. References to “employer” in this Agreement include Your employer or anyone else
for whom You are acting in making Your Submission, e.g. as a contractor, vendor, or agent. If Your
Submission is made in the course of Your work for an employer or Your employer has intellectual
property rights in Your Submission by contract or applicable law, You must secure permission from Your
employer to make the Submission before signing this Agreement. In that case, the term “You” in this
Agreement will refer to You and the employer collectively. If You change employers in the future and
desire to Submit additional Submissions for the new employer, then You agree to sign a new Agreement
and secure permission from the new employer before Submitting those Submissions.
Licenses.

Copyright License. You grant Microsoft, and those who receive the Submission directly or
indirectly from Microsoft, a perpetual, worldwide, non-exclusive, royalty-free, irrevocable license in the
Submission to reproduce, prepare derivative works of, publicly display, publicly perform, and distribute
the Submission and such derivative works, and to sublicense any or all of the foregoing rights to third
parties.
Patent License. You grant Microsoft, and those who receive the Submission directly or
indirectly from Microsoft, a perpetual, worldwide, non-exclusive, royalty-free, irrevocable license under
Your patent claims that are necessarily infringed by the Submission or the combination of the
Submission with the Project to which it was Submitted to make, have made, use, offer to sell, sell and
import or otherwise dispose of the Submission alone or with the Project.
Other Rights Reserved. Each party reserves all rights not expressly granted in this Agreement.
No additional licenses or rights whatsoever (including, without limitation, any implied licenses) are
granted by implication, exhaustion, estoppel or otherwise.

Representations and Warranties. You represent that You are legally entitled to grant the above
licenses. You represent that each of Your Submissions is entirely Your original work (except as You may
have disclosed under Section 3). You represent that You have secured permission from Your employer to
make the Submission in cases where Your Submission is made in the course of Your work for Your
employer or Your employer has intellectual property rights in Your Submission by contract or applicable
law. If You are signing this Agreement on behalf of Your employer, You represent and warrant that You
have the necessary authority to bind the listed employer to the obligations contained in this Agreement.
You are not expected to provide support for Your Submission, unless You choose to do so. UNLESS
REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING, AND EXCEPT FOR THE WARRANTIES
EXPRESSLY STATED IN SECTIONS 3, 4, AND 6, THE SUBMISSION PROVIDED UNDER THIS AGREEMENT IS
PROVIDED WITHOUT WARRANTY OF ANY KIND, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY OF
NONINFRINGEMENT, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE.
Notice to Microsoft. You agree to notify Microsoft in writing of any facts or circumstances of which
You later become aware that would make Your representations in this Agreement inaccurate in any
respect.
Information about Submissions. You agree that contributions to Projects and information about
contributions may be maintained indefinitely and disclosed publicly, including Your name and other
information that You submit with Your Submission.
Governing Law/Jurisdiction. This Agreement is governed by the laws of the State of Washington, and
the parties consent to exclusive jurisdiction and venue in the federal courts sitting in King County,
Washington, unless no federal subject matter jurisdiction exists, in which case the parties consent to
exclusive jurisdiction and venue in the Superior Court of King County, Washington. The parties waive all
defenses of lack of personal jurisdiction and forum non-conveniens.
Entire Agreement/Assignment. This Agreement is the entire agreement between the parties, and
supersedes any and all prior agreements, understandings or communications, written or oral, between
the parties relating to the subject matter hereof. This Agreement may be assigned by Microsoft.

github-actions

Automated Code Review

Reviewers: 5 | Confidence: 62% | Result: All clear

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

Automated review by ProgrammerPlus1998's agents

Copilot

🟡 Not ready to approve

There are correctness and reliability issues in the updated connector (notably streamable HTTP timeout semantics and server logging context handling under concurrency) that should be addressed before merging.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

This review doesn't count toward merge requirements. Sign up for the private preview to control whether Copilot approvals count.

Pull request overview

This PR migrates the Python MCP connector integration in Semantic Kernel to the MCP Python SDK 2.x API, unblocking installation alongside mcp>=2.0.0 and updating server/client behaviors and tests to match the breaking changes.

Changes:

Update python/semantic_kernel/connectors/mcp.py for MCP 2.x (server handler registration via Server(...), client transport/notification changes, snake_case model fields, httpx2-based streamable HTTP).
Bump dependency pins to mcp>=2.0.0,<3.0 and regenerate uv.lock.
Update MCP test assets and unit tests to match new SDK shapes and removal of websocket transport.

File summaries

File	Description
python/semantic_kernel/connectors/mcp.py	Migrates MCP server/client connector implementation to the MCP 2.x API and transport expectations.
python/pyproject.toml	Updates MCP dependency pins to require SDK 2.x.
python/tests/unit/connectors/mcp/test_mcp.py	Adapts unit tests/mocks to MCP 2.x request/response shapes and transport changes.
python/tests/assets/test_plugins/TestMCPPlugin/mcp_server.py	Updates test MCP server asset to the new server class.
python/uv.lock	Regenerates lockfile reflecting MCP 2.x transitive dependency changes (e.g., httpx2).

Review details

Suppressed comments (1)

python/semantic_kernel/connectors/mcp.py:930

This docstring says extra kwargs are passed to the websocket client constructor, but get_mcp_client() unconditionally raises because websocket transport was removed in mcp 2.x, so those kwargs are never used. Updating the docstring avoids misleading callers.

        Any extra arguments passed to the constructor will be passed to the
        websocket client constructor.

Files reviewed: 4/5 changed files
Comments generated: 2
Review effort level: Lite

We're testing this review assessment. Please use 👍 or 👎 to tell us if it's correct.

+    # In mcp 2.x there is no server-level request_context; handlers receive a per-request
+    # ServerRequestContext carrying the connection-scoped session. We track the most recent
+    # one so helper functions (e.g. _log) can reach the session to emit log messages.
+    current_ctx: dict[str, ServerRequestContext | None] = {"ctx": None}


+                timeout = httpx2.Timeout(
+                    self.timeout if self.timeout else 30.0,
+                    read=self.sse_read_timeout if self.sse_read_timeout else 300.0,
+                )


Copilot AI review requested due to automatic review settings August 3, 2026 11:09

ProgrammerPlus1998 requested a review from a team as a code owner August 3, 2026 11:09

Copilot started reviewing on behalf of ProgrammerPlus1998 August 3, 2026 11:10 View session

github-actions Bot reviewed Aug 3, 2026

View reviewed changes

Copilot AI reviewed Aug 3, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Python: migrate mcp connector to mcp 2.x - #14251

Python: migrate mcp connector to mcp 2.x#14251
ProgrammerPlus1998 wants to merge 1 commit into
microsoft:mainfrom
ProgrammerPlus1998:feat/mcp-2x-migration

ProgrammerPlus1998 commented Aug 3, 2026

Uh oh!

microsoft-github-policy-service Bot commented Aug 3, 2026

Contribution License Agreement

Uh oh!

microsoft-github-policy-service Bot commented Aug 3, 2026

Contribution License Agreement

Uh oh!

github-actions Bot left a comment

Uh oh!

Copilot AI left a comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Uh oh!

Conversation

ProgrammerPlus1998 commented Aug 3, 2026

Motivation and Context

Description

Contribution Checklist

Uh oh!

microsoft-github-policy-service Bot commented Aug 3, 2026

Contribution License Agreement

Uh oh!

microsoft-github-policy-service Bot commented Aug 3, 2026

Contribution License Agreement

Uh oh!

github-actions Bot left a comment

Choose a reason for hiding this comment

Automated Code Review

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟡 Not ready to approve

Suppressed comments (1)

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants