`add_issue_comment`, `update_issue`, and `get_issue` reject valid integer `issue_number`

[chriszhang08]

Summary

Three endpoints that take issue_number as a required parameter consistently fail when invoked with an integer, even though the tool schema declares issue_number as number. Other endpoints on the same server that take integer parameters work correctly, and the failure survives reconnecting the MCP server.

Affected tools

• add_issue_comment
• update_issue
• get_issue

Unaffected tools (for comparison, same session, same repo, same auth)

• create_issue — succeeds (does not take issue_number)
• list_issues, search_issues — succeed
• create_branch, create_or_update_file, push_files, create_pull_request — all succeed, including calls with integer fields like milestone

Reproduction

1. Any repo the caller can write issues on.
2. Call, e.g.:

   {
     "tool": "add_issue_comment",
     "arguments": {
       "owner": "<owner>",
       "repo": "<repo>",
       "issue_number": 11,
       "body": "test"
     }
   }

3. Call fails. Retrying multiple times, including after fully reconnecting the MCP server, reproduces the failure.
4. create_issue against the same repo in the same session succeeds, ruling out auth, permissions, and rate limiting.
5. Reproduced across at least two independent sessions on the same day.

Expected

Comment is posted / issue is updated / issue is fetched, matching a direct REST call to POST /repos/{owner}/{repo}/issues/{issue_number}/comments (etc.).

Actual

Call is rejected before it reaches GitHub. The failure pattern is consistent with issue_number being serialised as a string somewhere in the request pipeline and then rejected by the server's own integer validation.

[TODO fill in with error string on next occurrence]

Hypothesis

The three broken endpoints are exactly the ones where issue_number is templated into a URL path segment (/repos/{owner}/{repo}/issues/{issue_number}[/comments]), whereas the working endpoints pass their integers in the request body or query string. Likely culprits:

• A path-parameter substitution step stringifies the value before an internal validator runs.
• A schema-validation layer runs after path substitution and sees a string where a number is required.

Anywhere issue_number is interpolated into a URL is worth checking first.

Affected version

• MCP server: GitHub MCP http server
• Transport: stdio.
• Client: custom provider

Please run docker run -i --rm ghcr.io/github/github-mcp-server ./github-mcp-server --version and paste the output below

Workaround

None from the client side; the caller cannot influence how the server serialises the parameter. Affected users have to fall back to the GitHub REST API directly or edit the issue in the web UI.

[rpelevin]

This looks like an operation-identity boundary bug, not just a parameter type mismatch.

The invariant I would want is:

• the schema-accepted issue_number value should have one canonical representation from tool input through URL construction
• path interpolation must happen after validation, or it must preserve the typed value used for validation
• any coercion from number to path string should be recorded as transport serialization, not fed back into schema validation
• add_issue_comment, update_issue, and get_issue should share the same issue identity normalization contract
• rejection should produce a typed client-visible error that identifies schema stage vs path-construction stage without exposing token or repo secrets

Tests I would add:

• integer issue_number accepted for get_issue, update_issue, and add_issue_comment
• numeric-looking string rejected or normalized according to one documented rule, not depending on endpoint
• path-bound issue_number and query/body integer params use the same canonicalization test fixture
• failing validation returns no-effect evidence: no REST call made and no issue mutation
• retries with the same input produce the same request digest and error stage

That keeps MCP tool schemas honest while making issue mutations auditable before any GitHub write is attempted.

Boundary: architecture and conformance feedback only; no claim about GitHub/MCP Server alignment, implementation correctness, acceptance, partnership, integration, customer interest, official alignment, GitHub MCP usage, or Neura usage.