Python: Skip MCP tools and prompts whose normalized names collide - #14236
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SergeyMenshykh merged 3 commits intoJul 29, 2026
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MCP tool and prompt names are normalized to the allowed kernel function identifier pattern. The normalization is many-to-one, so two distinct remote names can produce the same local name. Previously the second registration replaced the first via setattr with no check, leaving a single kernel function whose displayed name no longer matched the remote item it invokes. Track the normalized names already registered by the plugin and skip any tool or prompt that would rebind a name owned by a different remote item, logging a warning instead. Reloading the same remote item still refreshes its function, and tools and prompts share one registry because both bind attributes on the same plugin instance. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 4cab25f4-d987-42b3-bb34-e8d8a7185c80
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Pull request overview
This PR hardens the Python MCP connector’s tool/prompt registration to avoid silent overwrites when different remote names normalize to the same local kernel function identifier, ensuring stable and correct dispatch to the intended remote MCP item.
Changes:
- Track already-registered normalized MCP names across loads (tools + prompts) and detect collisions.
- Skip colliding tools/prompts and emit a warning describing both the existing and conflicting remote items.
- Add unit tests covering collisions within a single load, across reloads, and between prompts vs tools.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| python/semantic_kernel/connectors/mcp.py | Adds persistent cross-load, cross-type collision tracking for normalized MCP names and logs warnings instead of overwriting registrations. |
| python/tests/unit/connectors/mcp/test_mcp.py | Adds unit tests validating collision detection/skip behavior for tools, prompts, reload scenarios, and prompt-vs-tool collisions. |
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The mcp requirement had no upper bound, and the Python CI workflows install with `uv sync -U`, which resolves to the newest release rather than the locked one. mcp 2.0.0 reorganizes the package, so `semantic_kernel/connectors/mcp.py` fails to import and every unit test job errors during collection. mcp 2.0 removes `mcp.client.websocket` and `mcp.shared.session`, relocates `McpError` and `RequestContext`, and renames `streamablehttp_client` to `streamable_http_client`. Supporting it requires a separate migration, so pin the supported range to `<2` in the base dependency and the mcp extra to keep CI resolving a compatible 1.x release. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 4cab25f4-d987-42b3-bb34-e8d8a7185c80
Resolve conflicts in python/pyproject.toml and python/uv.lock in favor of upstream. PR microsoft#14222 already constrained mcp to the 1.x series, so the local constraint added on this branch was redundant and is dropped in favor of the upstream `<2.0` specifier. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 4cab25f4-d987-42b3-bb34-e8d8a7185c80
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Python Test Coverage Report •
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eavanvalkenburg
approved these changes
Jul 29, 2026
SergeyMenshykh
enabled auto-merge
July 29, 2026 12:52
giles17
approved these changes
Jul 29, 2026
github-project-automation
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moved this from Sprint: In Review
to Sprint: Done
in Semantic Kernel
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Motivation and Context
MCP tool and prompt name normalization is many-to-one, so two remote names can produce the same local name. The second registration silently replaced the first.
Description
Track normalized names already registered by the plugin and skip colliding tools or prompts with a warning instead of overwriting. Reloading the same remote item still refreshes it. Adds unit tests.
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