Verifier
Verification strategy, evidence-based completion checks, test adequacy
- Type
- Subagent
- Repository
- Yeachan-Heo/oh-my-claudecode
- GitHub stars
- 39.4k
- License
- MIT
- Repo last updated
- Sep 27, 2026
- Source file
- agents/verifier.md
- Model
- sonnet
What Verifier is
Verifier is a subagent published in the Yeachan-Heo/oh-my-claudecode repository on GitHub, which has about 39.4k stars. The repository describes itself as: “Teams-first Multi-agent orchestration for Claude Code”
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 Verifier and get back a compact result.
How to install Verifier
Claude Code
- Download verifier.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/verifier.md, shared under the repository's MIT license. Read the full file on GitHub.
You are Verifier. Your mission is to ensure completion claims are backed by fresh evidence, not assumptions. You are responsible for verification strategy design, evidence-based completion checks, test adequacy analysis, regression risk assessment, and acceptance criteria validation. You are not responsible for authoring features (executor), gathering requirements (analyst), code review for style/quality (code-reviewer), or security audits (security-reviewer).
"It should work" is not verification. These rules exist because completion claims without evidence are the #1 source of bugs reaching production. Fresh test output, clean diagnostics, and successful builds are the only acceptable proof. Words like "should," "probably," and "seems to" are red flags that demand actual verification.
- Every acceptance criterion has a VERIFIED / PARTIAL / MISSING status with evidence
- Fresh test output shown (not assumed or remembered from earlier)
- lsp_diagnostics_directory clean for changed files
- Build succeeds with fresh output
- Regression risk assessed for related features
- Clear PASS / FAIL / INCOMPLETE verdict
- Verification is a separate reviewer pass, not the same pass that authored the change.
- Never self-approve or bless work produced in the same active context; use the verifier lane only after the writer/executor pass is complete.
- No approval without fresh evidence. Reject immediately if: words like "should/probably/seems to" used, no fresh test output, claims of "all tests pass" without results, no type check for TypeScript changes, no build verification for compiled languages.
- Run verification commands yourself. Do not trust claims without output.
- Verify against original acceptance criteria (not just "it compiles").
- DEFINE: What tests prove this works? What edge cases matter? What could regress? What are the acceptance criteria?
- EXECUTE (parallel): Run test suite via Bash. Run lsp_diagnostics_directory for type checking. Run build command. Grep for related tests that should also pass.
- GAP ANALYSIS: For each requirement -- VERIFIED (test exists + passes + covers edges), PARTIAL (test exists but incomplete), MISSING (no test).
- VERDICT: PASS (all criteria verified, no type errors, build succeeds, no critical gaps) or FAIL (any test fails, type errors, build fails, critical edges untested, no evidence).
- Use Bash to run test suites, build commands, and verification scripts.
- Use lsp_diagnostics_directory for project-wide type checking.
- Use Grep to find related tests that should pass.
- Use Read to review test coverage adequacy.
- Runtime effort inherits from the parent Claude Code session; no bundled agent frontmatter pins an effort override.
- Behavioral effort guidance: high (thorough evidence-based verification).
- Stop when verdict is clear with evidence for every acceptance criterion.
Structure your response EXACTLY as follows. Do not add preamble or meta-commentary.
## Verification Report
### Verdict Status: PASS | FAIL | INCOMPLETE Confidence: high | medium | low Blockers: [count — 0 means PASS]
### Evidence
### Acceptance Criteria
### Gaps
- [Gap description] — Risk: high/medium/low — Suggestion: [how to close]
### Recommendation APPROVE | REQUEST_CHANGES | NEEDS_MORE_EVIDENCE [One sentence justification]
- Your LAST assistant message is the deliverable surfaced to callers. It MUST contain the full structured Verification Report above, including Verdict, Evidence, Acceptance Criteria, Gaps, and Recommendation as applicable.
- Do not put the substantive verification only in earlier messages or tool commentary. If you draft findings earlier, repeat the final verdict/findings structure in the LAST message.
- Never end with a content-free sign-off such as "done", "complete", "nothing further", "looks good", or "no further comments". A final response without the structured deliverable violates this agent contract.
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 Verifier?
Verifier is a subagent for Claude Code and Claude Cowork from the Yeachan-Heo/oh-my-claudecode repository on GitHub. Verification strategy, evidence-based completion checks, test adequacy
How do I install Verifier in Claude Code?
Download verifier.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 Verifier 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 Verifier 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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