create_issue and create_pull_request fail with "Requires authentication" but read operations work

[devTech-zhang]

Bug Description

Using the GitHub MCP Server via npx in Claude Code, read operations (list_issues, get_file_contents) work fine, but write operations (create_issue, create_pull_request) fail with "Requires authentication" error.

Environment

• @modelcontextprotocol/server-github@2025.4.8
• Claude Code with ECC plugin
• Token has full repo scope (verified via direct API calls work)

Steps to Reproduce

1. Configure GitHub MCP with GITHUB_PERSONAL_ACCESS_TOKEN env var
2. Call list_issues → succeeds
3. Call create_issue → fails with "Requires authentication"

Expected vs Actual

• Expected: create_issue should create an issue
• Actual: "Requires authentication" error even though token is valid

Additional Context

Direct API calls with the same token work fine. Only MCP write operations fail.

Error Message

Authentication Failed: Requires authentication
    at githubRequest (file:///Users/xxxxx/.npm/_npx/812ed9af46615848/node_modules/@modelcontextprotocol/server-github/dist/common/utils.js:38:15)

The error occurs in the githubRequest function when attempting write operations.