fix: make bash tool description parameter optional

[danielcherubini]

Issue for this PR

Closes #13146

Also:

• bash description #17415 — same error, Ubuntu
• Bash tool called with invalid arguments: "expected string, received undefined" for command and description fields #14519 — both command and description undefined, Windows
• The bash tool was called with invalid arguments: #10213 — same error
• Getting stuck at 'Running commands' > Shell > undefined #5662 — shell hangs with "undefined"

Related (local/small model tool schema issues):

• Weird error with toolcalling on local model #6649 — local model tool call parsing
• qwen3-coder fails to call edit tool #6918 — Qwen3-Coder edit tool fails
• Write tool called with invalid parameters #18131 — Qwen 3.5 35B write tool fails
• Silent agent crash and subsequent 400 Bad Request with local vLLM (Qwen 3 XML Tools) #16488 — Qwen 3 vLLM silent crash

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The description parameter on the bash tool is required but some models (especially smaller/local models) don't always include it in tool calls, causing "Invalid input: expected string, received undefined" errors that loop indefinitely. Make it optional and fall back to the command string when not provided.

If you paste a large clearly AI generated description here your PR may be IGNORED or CLOSED!

How did you verify your code works?

I ran opencode in two different repos, using small and larger models and found no issue with the error I have seen in issue #13146

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate PRs Found:

1. PR fix(bash): make description optional for tool calls #13288: fix(bash): make description optional for tool calls

   • fix(bash): make description optional for tool calls #13288
   • Addresses the same issue of making bash tool description optional

2. PR fix(bash): make description parameter optional in bash tool #13832: fix(bash): make description parameter optional in bash tool

   • fix(bash): make description parameter optional in bash tool #13832
   • Nearly identical fix with same title structure and purpose

These PRs appear to address the exact same issue as PR #18392 - making the bash tool's description parameter optional to handle cases where smaller/local models don't include it in tool calls. You should check the status of these existing PRs before proceeding with PR #18392.