Make branch parameter optional in create_pull_request and push_to_pull_request_branch MCP tools

[Copilot]

Summary

Updates the create_pull_request and push_to_pull_request_branch MCP tool handlers to make the "branch" parameter optional. When the branch parameter is not provided or is empty, the current git branch is automatically resolved using git rev-parse --abbrev-ref HEAD.

Problem

Previously, both MCP tools required an explicit "branch" parameter:

// create_pull_request - branch was required
{
  "title": "My PR",
  "body": "Description",
  "branch": "feature-branch"  // Required - would fail without this
}

// push_to_pull_request_branch - branch was required
{
  "message": "Update files",
  "branch": "feature-branch"  // Required - would fail without this
}

This created unnecessary friction when the AI agent was already working on a specific branch and just wanted to create a PR or push changes from the current branch.

Solution

The branch parameter is now optional for both tools. When omitted, the MCP server automatically resolves the current git branch:

// create_pull_request - branch is now optional
{
  "title": "My PR",
  "body": "Description"
  // branch parameter omitted - will use current branch
}

// push_to_pull_request_branch - branch is now optional
{
  "message": "Update files"
  // branch parameter omitted - will use current branch
}

Implementation Details

1. Added getCurrentBranch() helper function that executes git rev-parse --abbrev-ref HEAD to resolve the current branch name

2. Created custom handlers for both tools:

   • createPullRequestHandler() - Resolves current branch when not provided
   • pushToPullRequestBranchHandler() - Resolves current branch when not provided

3. Updated tool schemas:

   • Removed "branch" from required fields
   • Updated descriptions to indicate the parameter is optional
   • Documented the fallback behavior

Backward Compatibility

The changes are fully backward compatible. Existing calls that provide an explicit "branch" parameter will continue to work unchanged:

// This still works exactly as before
{
  "title": "My PR",
  "body": "Description",
  "branch": "custom-branch"  // Explicit branch still works
}

Testing

• Added comprehensive test coverage for the optional parameter behavior
• Verified schema changes are correctly applied
• All 439 JavaScript tests pass
• All Go unit tests pass
• Manual verification of branch resolution logic

Files Changed

• pkg/workflow/js/safe_outputs_mcp_server.cjs - Core implementation
• pkg/workflow/js/safe_outputs_mcp_server_defaults.test.cjs - Test coverage

Original prompt

Update create_pull_request and push_to_pull_request_branch MCP tool handlers such that "branch" is optional. If branch is missing, the current branch is used.

• update the mcp server tool descriptions
• update the mcp server to resolve the current git branch when processing the message in the mcp handler.

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[pelikhan]

@copilot use exec.getExecOutput who is defined in @actions/core (it is already ambient in the actions/github-script execution environment)