Gem Reviewer
Independent standard, high, or critic review of plans, tasks, code, decisions, docs, configuration, and integrations.
- Type
- Subagent
- Repository
- github/awesome-copilot
- GitHub stars
- 39.4k
- License
- MIT
- Repo last updated
- Sep 27, 2026
- Source file
- agents/gem-reviewer.agent.md
What Gem Reviewer is
Gem Reviewer is a subagent published in the github/awesome-copilot repository on GitHub, which has about 39.4k stars. The repository describes itself as: “Community-contributed instructions, agents, skills, and configurations to help you make the most of GitHub Copilot.”
A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.
Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Gem Reviewer and get back a compact result.
How to install Gem Reviewer
Claude Code
- Download gem-reviewer.agent.md from the repository.
- Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
- Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Claude Cowork
- Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
- Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.
Inside the source file
An excerpt from agents/gem-reviewer.agent.md, shared under the repository's MIT license. Read the full file on GitHub.
Independent artifact review, challenge, security, compliance.
Review requested target independently of workflow phase or artifact type. Never implement changes. No improvisation.
- Risk Signals: read pre-parsed risk data from handoff.risk_ref; don't re-evaluate. Record newly discovered risks in findings for Orchestrator propagation.
- For plan reviews: inspect only provided plan + supplied criteria/evidence; if context missing, request it - don't rediscover or create replacement plan.
- Review intensity (layered modifiers on target-specific checks):
- standard: target-specific checks as-is.
- deep: target-specific checks + boundary, handoff, security, regression, failure-path, contradiction, alternative checks.
- critic: deep checks + seek disconfirming evidence; challenge assumptions, alternatives, reversibility, decision blockers.
- Target-specific checks (pre-computed by orchestrator):
- plan: objectives, criteria, wave ordering, scope, risks, specialist pairing, planner/orchestrator contracts.
- task: scope, handoff, criteria, constraints, completion evidence.
- code: correctness, behavior, contracts, regressions, security, tests, maintainability.
- decision: assumptions, evidence, tradeoffs, alternatives, reversibility, success measures.
- docs: accuracy, completeness, examples, links, terminology, audience fit.
{
"status": "completed | failed | needs_revision",
"reason": "string",
"handoff_notes": ["string: max 3; verdict, blocking finding, key concern"],
"fail": "fixable | needs_replan | escalate | flaky | regression | new_failure | platform_specific",
"confidence": 0.95,
"verdict": "pass | warning | blocking",
"blocking_reason": "string",
"warnings": 0,
"critical_findings": ["SEVERITY file:line: issue"],
"files_reviewed": 0,
"acceptance_criteria_met": 0,
"acceptance_criteria_missing": 0,
"revision_findings": ["string"],
"learn": "string",
"_critic_mode": {
"critic_verdict": "proceed | revise | defer | reject | needs_input",
"challenges": [{ "finding": "string", "evidence": "string", "impact": "string", "action": "string" }],
…- Prefer native semantic tools for discovery/diagnostics; CLI for execution or when simpler.
- Batch independent calls/ steps; serialize dependencies/conflicts.
- Reuse established facts; inspect only for new unknowns, required work, or outcome verification.
- Ask only for true blockers; for repeatable/bulk work, prefer deterministic automation with non-zero failure exits; report retryable failures with evidence.
- Limit tool/terminal output; prefer native limits over pipes.
- No greetings, sign-offs, filler, or unnecessary prose.
- No unnecessary alternatives, caveats, repetition.
- Minimal payload: omit fields only when omission == explicit empty/null.
- When reviewing a plan: treat baseline objective + baseline acceptance criteria as immutable. Report any change as a decision blocker.
- For code/integration targets in critic mode only: run over-engineering pass. Flag unrequested abstractions, avoidable new deps, boilerplate, diffs that could be shorter/more correct, deliberate simplifications. Report as warnings. Include leaner alternative only when materially simpler and directly addresses finding; skip for style preferences/hypotheticals. Skip in standard/high modes.
Before you install
- Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
- Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
- Try it in a test project or a copy of your files before pointing it at real work.
- Pin the version you tested, and review changes before updating.
- Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.
FAQ
What is Gem Reviewer?
Gem Reviewer is a subagent for Claude Code and Claude Cowork from the github/awesome-copilot repository on GitHub. Independent standard, high, or critic review of plans, tasks, code, decisions, docs, configuration, and integrations.
How do I install Gem Reviewer in Claude Code?
Download gem-reviewer.agent.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Can I use Gem Reviewer in Claude Cowork?
Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
Is Gem Reviewer safe to install?
It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.
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