fix(opencode): make bash tool description parameter optional

[RheagalFire]

Issue for this PR

Closes #20669

Type of change

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

What does this PR do?

The bash tool's description parameter is defined as Schema.String (required) in prompt.ts. Local OpenAI-compatible backends like llama.cpp, LM Studio, and LiteLLM sometimes omit this field when calling the
tool. This causes validation to fail with expected string, received undefined, killing the agent loop.

The fix:

• prompt.ts: Changed Schema.String to Schema.optional(Schema.String) for the description parameter
• shell.ts: Added ?? "" fallback where params.description is passed downstream, since the type is now string | undefined

The prompt text already says "it is very helpful if you write a clear, concise description" which implies optional behavior. This aligns the schema with that intent.

How did you verify your code works?

• bun turbo typecheck passes (12/12 packages)
• Husky pre-push hook passes

Checklist

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

[github-actions]

Hey! Your PR title Fix/bash description optional doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

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

Potential Duplicate Found:

• PR fix: make bash tool description parameter optional #18392: "fix: make bash tool description parameter optional"
  • fix: make bash tool description parameter optional #18392
  • Why related: This PR appears to address the exact same issue - making the bash tool's description parameter optional. This is likely a duplicate or supersedes the earlier fix.

Related PR:

• PR fix(opencode): improve local OpenAI-compatible backend robustness #20668: "fix(opencode): improve local OpenAI-compatible backend robustness"
  • fix(opencode): improve local OpenAI-compatible backend robustness #20668
  • Why related: This PR is referenced in the issue (Default agent is brittle against local OpenAI-compatible tool-call quirks #20669) and may be related to the same backend compatibility problem with optional parameters.