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Guard list_code_scanning_alerts workflow usage to prevent MCP context overflow #27657

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pelikhan merged 5 commits into from
Apr 21, 2026
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Guard list_code_scanning_alerts workflow usage to prevent MCP context overflow #27657

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3029209
Initial plan
Copilot Apr 21, 2026
ad2f9e8
chore: outline plan for code scanning alert pagination guard
Copilot Apr 21, 2026
4f3b390
Revert "chore: outline plan for code scanning alert pagination guard"
Copilot Apr 21, 2026
1ef1915
fix: guard list_code_scanning_alerts usage in workflow prompts
Copilot Apr 21, 2026
aef95c0
docs: clarify code scanning alert guardrails for MCP usage
Copilot Apr 21, 2026
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11 changes: 7 additions & 4 deletions .github/workflows/code-scanning-fixer.md
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Expand Up @@ -60,7 +60,7 @@ You are a security-focused code analysis agent that automatically fixes code sca

Your goal is to:
1. **Check cache for previously fixed alerts**: Avoid fixing the same alert multiple times
2. **List all open alerts**: Find all open code scanning alerts (prioritizing by severity: critical, high, medium, low, warning, note, error)
2. **List open high-risk alerts**: Find open critical/high code scanning alerts (prioritizing critical over high)
3. **Select an unfixed alert**: Pick the highest severity unfixed alert that hasn't been fixed recently
Comment on lines +63 to 64
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Copilot AI Apr 21, 2026

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The workflow now scopes itself to critical/high alerts, but the surrounding text still implies it handles “all severity levels” (see the earlier intro) and selects from “all open alerts”. Please update the description/wording to consistently reflect the high-risk-only scope so readers don’t expect medium/low handling from this workflow.

This issue also appears in the following locations of the same file:

  • line 84
  • line 88

Copilot uses AI. Check for mistakes.
4. **Analyze the vulnerability**: Understand the security issue and its context
5. **Generate a fix**: Create code changes that address the security issue
Expand All @@ -84,15 +84,18 @@ Use the GitHub MCP server to list all open code scanning alerts:
- `owner`: "githubnext" (the repository owner)
- `repo`: "gh-aw" (the repository name)
- `state`: "open"
- Do NOT filter by severity - get all alerts
- `severity`: "critical,high" (required to prevent oversized MCP responses)
- Medium/low/warning/note/error are intentionally excluded in this workflow so each run stays within MCP context limits
- Do NOT send `head_limit` to the default GitHub MCP tool (`list_code_scanning_alerts` does not support it)
- If using a custom wrapper that explicitly documents `head_limit`, you may use `head_limit: 20`
- Sort the results by severity (prioritize: critical > high > medium > low > warning > note > error)
- If no open alerts are found, log "No unfixed security alerts found. All alerts have been addressed!" and exit gracefully
- If you encounter tool errors, report them clearly and exit gracefully rather than trying workarounds
- Create a list of alert numbers from the results, sorted by severity (highest first)

### 3. Select an Unfixed Alert

From the list of all open alerts (sorted by severity):
From the list of open high-risk alerts (sorted by severity):
- Exclude any alert numbers that are in the cache (already fixed)
- Select the first alert from the filtered list (highest severity unfixed alert)
- If no unfixed alerts remain, exit gracefully with message: "No unfixed security alerts found. All alerts have been addressed!"
Expand Down Expand Up @@ -189,7 +192,7 @@ After successfully creating the pull request:

## Security Guidelines

- **All Severity Levels**: Fix security alerts of all severities (prioritizing critical, high, medium, low, warning, note, error in that order)
- **High-Risk Only**: This workflow only processes critical/high alerts to keep MCP responses bounded and actionable
- **Minimal Changes**: Make only the changes necessary to fix the security issue
- **No Breaking Changes**: Ensure the fix doesn't break existing functionality
- **Best Practices**: Follow security best practices for the specific vulnerability type
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4 changes: 3 additions & 1 deletion .github/workflows/github-mcp-structural-analysis.md
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Expand Up @@ -75,7 +75,9 @@ Test ONE representative tool from each toolset with minimal parameters:
3. **issues**: `list_issues` - List issues with perPage=1
4. **pull_requests**: `list_pull_requests` - List PRs with perPage=1
5. **actions**: `list_workflows` - List workflows with perPage=1
6. **code_security**: `list_code_scanning_alerts` - List alerts with minimal params
6. **code_security**: `list_code_scanning_alerts`
- Required guard params: `state: open`, `severity: critical,high`
- `head_limit` note: the GitHub MCP server's `list_code_scanning_alerts` tool does not support `head_limit`; use `head_limit: 20` only with custom wrappers that explicitly document support
7. **discussions**: `list_discussions` (if available)
8. **labels**: `get_label` - Get a single label
9. **users**: `get_user` (if available)
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2 changes: 2 additions & 0 deletions AGENTS.md
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Expand Up @@ -166,6 +166,8 @@ network:
- **Never use `mode: remote`** — it does not work with the GitHub Actions token (`GITHUB_TOKEN`) and requires a special PAT or GitHub App token
- Never rely on direct `api.github.com` access in Copilot workflows
- **Never use direct GitHub CLI API reads in agent prompts** (for example: `gh api`, `gh repo view`, `gh pr list`) — use MCP `github` tools instead
- **Guard `list_code_scanning_alerts` calls in workflow prompts**: always include `state: open` and `severity: critical,high` to avoid oversized MCP responses
- **`head_limit` compatibility**: do **not** send `head_limit` to the default GitHub MCP tool; use `head_limit: 20` only with custom wrappers after verifying support in wrapper docs or wrapper-specific tests

See [GitHub MCP Server Documentation](skills/github-mcp-server/SKILL.md) for complete configuration details.

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