tools/mcp: pin mcp<2 to fix unit CI collection

[Fridah-nv]

What does this PR do?

Type of change: Bug fix (CI)

mcp==2.0.0 was released and removed the mcp.server.fastmcp module (the 2.0 SDK replaces it with mcp.server.mcpserver). tools/mcp/pyproject.toml declared an unpinned mcp>=1.0, so CI now resolves mcp==2.0.0, and tools/mcp/modelopt_mcp/server.py's from mcp.server.fastmcp import FastMCP fails at import:

ModuleNotFoundError: No module named 'mcp.server.fastmcp'
ERROR collecting tools/mcp/tests/test_bridge.py

This breaks the mcp unit job — and thus the unit-pr-required-check gate — on every PR whose diff touches pyproject.toml, noxfile.py, or .github/workflows/unit_tests.yml (the changed-files paths that trigger the mcp job).

This PR pins mcp>=1.0,<2, keeping the 1.x line that still ships mcp.server.fastmcp. Migrating the server to the mcp 2.0 API (mcp.server.mcpserver) is a larger change tracked separately.

Usage

# N/A - dependency pin only

Testing

• uv pip install -e tools/mcp now resolves an mcp 1.x wheel, so from mcp.server.fastmcp import FastMCP imports and tools/mcp/tests/test_bridge.py collects again.

Before your PR is "Ready for review"

• Is this change backward compatible?: ✅
• If you copied code from any other sources or added a new PIP dependency, did you follow guidance in CONTRIBUTING.md: N/A — tightens an existing dependency's upper bound.
• Did you write any new necessary tests?: N/A — restores collection of the existing tools/mcp tests.
• Did you update Changelog?: N/A — CI/build fix, nothing user-facing in the wheel.
• Did you get Claude approval on this PR?: ❌

Additional Information

Unblocks the unit-pr-required-check gate for in-flight PRs (surfaced on #2000). Follow-up: migrate modelopt_mcp/server.py to the mcp 2.0 API and relax the pin.

Summary by CodeRabbit

• Bug Fixes
  • Prevented compatibility issues by limiting the MCP package to supported version 1.x releases.

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 87c9f8c and 027d916.

📒 Files selected for processing (1)

• tools/mcp/pyproject.toml

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📝 Walkthrough

Walkthrough

The MCP dependency constraint changes from mcp>=1.0 to mcp>=1.0,<2, with a comment documenting the mcp.server.fastmcp compatibility issue.

Changes

MCP compatibility

Layer / File(s)	Summary
Constrain MCP dependency tools/mcp/pyproject.toml	Limits MCP to versions below 2.0 and documents the removed mcp.server.fastmcp module.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Suggested reviewers: kevalmorabia97, chenhanyu

🚥 Pre-merge checks | ✅ 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly reflects the main change: pinning mcp below 2 to restore CI/test collection.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Security Anti-Patterns	✅ Passed	PR only tightens mcp version in tools/mcp/pyproject.toml; no modelopt/examples Python changes or new insecure patterns were added.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fridah/fix-mcp-ci-pin

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.83%. Comparing base (33d05b0) to head (027d916).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2026   +/-   ##
=======================================
  Coverage   66.83%   66.83%           
=======================================
  Files         519      519           
  Lines       58916    58916           
=======================================
  Hits        39376    39376           
  Misses      19540    19540           

Flag	Coverage Δ
unit	54.89% <ø> (ø)

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[github-actions]

PR Preview Action v1.8.1
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2026-07-29 04:34 UTC