MCP GitHub server: Pull Request creation fails with merge_commit_sha error

[FaustoS88]

When trying to create a pull request using the GitHub MCP server, the operation consistently fails with the following error:

Error: MCP error -32603: Invalid arguments: merge_commit_sha: Expected string, received null

Steps to Reproduce

1. Set up Claude Desktop with GitHub MCP server
2. Create repository and branches successfully
3. Push changes to different branches
4. Attempt to create a pull request using create_pull_request function

Expected Behavior

Pull request should be created successfully between branches

Actual Behavior

Error about missing merge_commit_sha is returned

Environment

• Claude Desktop with MCP
• GitHub MCP server
• All other GitHub operations (create repository, push files, create branches) work correctly
• Manual PR creation through GitHub interface works

Additional Context

The merge_commit_sha parameter appears to be required by the implementation but should potentially be handled internally by the GitHub API.

Would appreciate guidance on whether this is a known issue or if there's a workaround available.