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fix(mcpserver): avoid collisions when prefixing reserved tool parameter names - #3740

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nikolas-sapa:fix/tool-param-model-dump-collision-3710
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nikolas-sapa wants to merge 1 commit into
modelcontextprotocol:mainfrom
nikolas-sapa:fix/tool-param-model-dump-collision-3710

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Fixes #3710

Summary

  • Prevents collisions between tool arguments and prefixed internal field names when a tool parameter shadows ArgModelBase attributes (e.g. model_dump).
  • When generating candidate field names, checks for collisions with other declared parameters, existing dynamic model parameters, and ArgModelBase attributes, appending an incremental counter when needed.
  • Adds test coverage for multiple collision scenarios and tool execution with prefixed parameters.

Motivation

When tools define parameters with names that shadow ArgModelBase/Pydantic attributes (such as model_dump), func_metadata prefixes the internal attribute name with field_. If a tool also accepts a parameter named field_, the previous implementation produced duplicate field definitions and overwrote fields.

@github-actions github-actions Bot added the missing-issue-link Auto-closed: PR needs a linked issue assigned to its author (see CONTRIBUTING.md) label Oct 22, 2026
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This PR has been closed automatically. This repo only keeps pull requests open when they come from a maintainer, or from a contributor a maintainer has assigned to the linked issue, and you aren't currently assigned to #3710.

If a maintainer assigns you to #3710, this PR reopens on its own and there's nothing more you need to do here. Assignment is a maintainer call based on capacity; comments that only ask to be assigned don't factor in. What does help is engaging on the issue itself by confirming the repro, explaining why it matters for your use case, or describing the approach you'd take.

You're welcome to keep pushing commits here (just avoid force-pushing, since GitHub can't reopen a rewritten branch), but that on its own won't get the PR reviewed or the issue assigned, and realistically most auto-closed PRs stay closed. There's no need to open a new PR either way.

CONTRIBUTING.md has the full reasoning, but in short:

  • We're a small team with very little capacity to review community PRs right now.
  • Many recent PRs are AI-generated with little human review, and reviewing one carefully still costs a maintainer as much time as it ever did. A well-described issue is usually more useful to us than the code.

Maintainers: reopen, remove missing-issue-link, or add bypass-issue-check to override.

@github-actions github-actions Bot closed this Oct 22, 2026
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Tool parameters model_dump and field_model_dump collide in the generated input schema

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