Hosted MCP `get_check_runs` fails with 403 where the equivalent REST call succeeds

從 get_check_runs 方法的 pull_request_read 入口開始，將其 hosted 驗證與權限路徑與此處描述的成功 REST 請求進行比較。檢查 #1942 引入的變更；完成的標準是：對於回報的 private repository 情況，hosted 方法能夠回傳 check runs；或者在無法變更 hosted installation 的情況下，明確記錄所需的權限。

Describe the bug

pull_request_read with method: get_check_runs returns 403 Resource not accessible by personal access token [] for a private repo that the same classic PAT can read via the plain REST API (gh pr checks / GET /repos/{owner}/{repo}/commits/{ref}/check-runs). Every other pull_request_read method (get, get_files, get_reviews, get_review_comments, etc.) works with that token on the same PR — only get_check_runs fails.

This means the method shipped via #1942 is effectively unusable against repos where the user's PAT is fine but the underlying MCP app installation is missing Checks: Read. The caller cannot fix it by adding PAT scopes, since the failing call isn't authenticated with the caller's PAT permission surface.

Affected version

Hosted remote MCP at https://api.githubcopilot.com/mcp/. github-mcp-server --version not available for the hosted deployment.

Steps to reproduce the behavior

1. Authenticate the hosted Copilot MCP with a classic PAT that has repo, read:org, and SSO authorization for the org hosting a private repo.k
2. Invoke mcp__github__pull_request_read with:

   method: get_check_runs
   owner: <org>
   repo:  <private-repo>
   pullNumber: <N>
   

3. From a local shell using the same PAT:

   gh api /repos/<org>/<private-repo>/commits/<head-sha>/check-runs
   

   returns 200 with the full check-runs payload.

Expected vs actual behavior

Expected: MCP get_check_runs returns the same payload as the REST API.

Actual:

failed to get check runs: GET https://api.github.com/repos/<org>/<private-repo>/commits/<sha>/check-runs?page=1&per_page=30: 403 Resource not accessible by personal access token []

All other pull_request_read methods succeed against the same PR with the same token.

Logs

Error string as surfaced to the MCP client:

failed to get check runs: GET https://api.github.com/repos/<org>/<private-repo>/commits/<sha>/check-runs?page=1&per_page=30: 403 Resource not accessible by personal access token []

Notes

• Feature was added in #1942 (closed). This report is a regression / follow-up: the method is reachable but consistently 403s under hosted-MCP auth where the caller's PAT has repo.
• Likely fix direction: ensure the hosted MCP's GitHub App installation requests Checks: Read, or document the fine-grained permission requirement alongside the tool description.

Remark: This issue was analyzed and the report was created with Claude Code.