Missing tool: list_issue_comments for reading general PR/issue comments

[mol-george]

GitHub Issue Draft for modelcontextprotocol/servers

Title

Missing tool: list_issue_comments for reading general PR/issue comments

Body

Summary

The GitHub MCP server is missing a critical tool for reading issue comments, creating an asymmetric API where users can write general PR/issue comments but cannot read them programmatically.

Related Issues & PRs

Previous Missing Tools Issues:

• #493: "Github MCP server has only half its claimed tools available" (January 2025)
• #541: "GitHub MCP Server missing some tools from the listed features" (January 2025)

Fix Attempt:

• #728: "Add missing pull request operations to MCP server" (March 2025) - MERGED
  • Fixed: get_pull_request, list_pull_requests, create_pull_request_review, merge_pull_request, get_pull_request_files, get_pull_request_status, update_pull_request_branch, get_pull_request_comments, get_pull_request_reviews
  • Missing: Issue comment reading functionality was not included

Current State

✅ Working (Write Operation):

• Tool: add_issue_comment
• GitHub API: POST /repos/{owner}/{repo}/issues/{issue_number}/comments
• Functionality: Can successfully add general comments to PRs/issues

❌ Missing (Read Operation):

• No corresponding read tool exists
• GitHub API: GET /repos/{owner}/{repo}/issues/{issue_number}/comments
• Impact: Cannot read general PR/issue comments programmatically

Expected Behavior

There should be a tool (e.g., list_issue_comments or get_issue_comments) that allows reading issue comments, following the same pattern as other GitHub resources and completing the fix from PR #728.

Reproduction Steps

1. Setup: Use any GitHub MCP server integration (tested with Claude Code)

2. Create issue comment:

   add_issue_comment(owner="mol-george", repo="ads", issue_number=20, body="test comment")
   

   ✅ Result: Successfully creates comment

3. Attempt to read comments:

   • No tool available for GET /repos/{owner}/{repo}/issues/{issue_number}/comments
   • ❌ Result: Cannot read the comment that was just created

4. Verify comments exist:

   get_issue(owner="mol-george", repo="ads", issue_number=20)
   

   ✅ Result: Shows "comments": 2 confirming comments exist but are unreadable via MCP

Technical Analysis

API Pattern Inconsistency

Resource	List/Read Tool	Create/Write Tool	Complete?
Issues	✅ list_issues	✅ create_issue	✅
Pull Requests	✅ list_pull_requests	✅ create_pull_request	✅
PR Review Comments	✅ get_pull_request_comments	✅ create_pull_request_review	✅
Issue Comments	❌ MISSING	✅ add_issue_comment	❌

GitHub API Support

The GitHub REST API fully supports reading issue comments:

• Endpoint: GET /repos/{owner}/{repo}/issues/{issue_number}/comments
• Documentation: https://docs.github.com/en/rest/issues/comments
• Authentication: Same requirements as existing working tools
• Permissions: Same requirements as add_issue_comment

Suggested Implementation

Add a new tool with signature:

list_issue_comments(
  owner: string,
  repo: string,
  issue_number: number,
  since?: string,  // Optional: only comments updated after this time
  per_page?: number, // Optional: pagination
  page?: number     // Optional: pagination
)

Returns: Array of issue comment objects matching GitHub API response format.

Impact

This missing functionality affects:

• PR workflow automation: Cannot read comment threads programmatically
• Issue management: Cannot process user feedback in comments
• GitHub integrations: Incomplete API coverage breaks automation workflows
• Developer experience: Asymmetric API creates confusion and limitations

Distinction from Fixed Tools

What PR #728 Fixed Successfully:

• ✅ get_pull_request_comments - Reads review comments (code line-specific comments)
• ✅ get_pull_request_reviews - Reads reviews (overall PR reviews)

What's Still Missing:

• ❌ list_issue_comments - Read issue comments (general conversation comments)

GitHub Comment Types Explained:

1. Issue Comments: General conversation on PRs/issues (/issues/{id}/comments) - Missing read tool
2. Review Comments: Code line-specific comments (/pulls/{id}/comments) - Fixed in #728
3. Reviews: Overall PR reviews with approval/changes (/pulls/{id}/reviews) - Fixed in #728

Workarounds

Currently users must:

1. Use GitHub web interface to read comments manually
2. Use gh CLI for comment reading
3. Implement custom API calls outside MCP
4. Use only review comments (line-specific) which do have read tools

Environment

• GitHub MCP Server: Version available in Claude Code (June 2025)
• Test Repository: https://github.com/mol-george/ads/pull/20
• Authentication: Working (can create issues, PRs, and comments)
• Permissions: Full repository access

Test Evidence

Live Test PR: https://github.com/mol-george/ads/pull/20

Test Results:

1. ✅ Created issue comment via add_issue_comment - Confirmed working
2. ❌ Cannot read issue comments - no tool available
3. ✅ Confirmed comments exist via get_issue showing "comments": 2
4. ✅ Review comments work perfectly via get_pull_request_comments (fixed in #728)
5. ✅ Reviews work perfectly via get_pull_request_reviews (fixed in #728)

This demonstrates the asymmetric implementation clearly - PR #728 fixed review-related reading but missed issue comment reading.

---

Priority: Medium (affects core GitHub workflow functionality) Effort: Low (follows existing patterns, GitHub API already supports it, similar to tools fixed in #728) Benefit: High (completes the missing piece of GitHub integration)

This issue represents the final gap in the GitHub MCP server's comment functionality that wasn't addressed in the comprehensive fix of PR #728.