# Toru Oizumi Claude Harness Engineering Pr Review Multi Model > Multi-Model PR Review (3 Amigos) - Skill: `tomevault-io/toru-oizumi-claude-harness-engineering-pr-review-multi-model` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/toru-oizumi-claude-harness-engineering-pr-review-multi-model` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/toru-oizumi-claude-harness-engineering-pr-review-multi-model/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/toru-oizumi-claude-harness-engineering-pr-review-multi-model --- # Multi-Model PR Review (3 Amigos) A PR review agent that runs three specialized reviewers in parallel, each on a different model, then merges their findings into a single structured review comment. The design rationale is in `docs/RATIONALE.md`. ## When to Use - Reviewing PRs that touch critical paths (auth, data layer, proto schemas, billing) - Reviewing PRs from team members when you want a second opinion before merging - Self-reviewing your own PR before asking a human to look - Post-incident review (re-review a PR that caused a bug to learn what was missed) ## When NOT to Use - Trivial PRs (typo fix, readme update, dependency bump) — the cost isn't worth it - When you don't have API keys configured for all three providers - When the PR contains secrets or production data (use local review instead) ## The 3 Amigos | Role | Model | Focus | | --- | --- | --- | | **Architect Reviewer** | Claude Sonnet (API) | Design principles, dependency direction, layer violations, abstraction level | | **Bug Hunter** | Gemini 2.5 Pro (API) | Race conditions, null/nil handling, edge cases, security, error swallowing | | **DX Reviewer** | DeepSeek Chat (API) | Naming, testability, readability, test coverage, public API clarity | Each runs independently on the full PR diff + repo context. They don't see each other's reviews (by design — avoid groupthink). ## Architecture ``` ┌─────────────────────┐ │ GitHub webhook / │ │ /harness:review-pr │ └──────────┬──────────┘ │ ┌──────▼──────┐ │ Mastra │ (Supervisor) │ Orchestrator│ └──────┬──────┘ │ parallel ┌────────────────┼────────────────┐ ▼ ▼ ▼ ┌────────────┐ ┌────────────┐ ┌────────────┐ │ Architect │ │ Bug Hunter │ │ DX Review │ │ (Sonnet) │ │ (Gemini) │ │ (DeepSeek) │ └──────┬─────┘ └──────┬─────┘ └──────┬─────┘ │ │ │ └────────────────┼────────────────┘ ▼ ┌────────────┐ │ Merger │ (Claude Sonnet) │ + Dedup │ └──────┬─────┘ ▼ Structured review comment ``` ## Why API keys, not Claude Max Claude Max plan OAuth inside a third-party orchestrator (Mastra server, GitHub Actions) is a ToS grey area. The plugin uses Anthropic API keys server-side to avoid this risk. Claude Max is reserved for local Claude Code use only. ## Setup ### 1. Configure API keys Create `.env` in the Mastra project (NOT in this plugin's repo): ```bash ANTHROPIC_API_KEY=sk-ant-... GEMINI_API_KEY=... DEEPSEEK_API_KEY=... GITHUB_TOKEN=ghp_... ``` ### 2. Deploy the Mastra server The plugin does not ship the Mastra server itself — that lives in your own repo (one per deployment). A minimal starter is in the [Mastra github-pr-code-review-agent template](https://github.com/mastra-ai/mastra/tree/main/examples). Recommended deployment target: GitHub Actions (simplest, already authenticated to your repo) or ECS Fargate (if you want it always-on for faster response). ### 3. Wire the GitHub webhook On PR open / synchronize → POST the PR number to the Mastra server endpoint. The server pulls the diff, runs the 3 Amigos, and posts a review comment back via `GITHUB_TOKEN`. ## Running locally Once the Mastra server is reachable: ``` /harness:review-pr ``` Output format: a single markdown comment with three sections: ```markdown ## Multi-Model Review ### 🏛 Architect (Claude Sonnet) - ... ### 🐛 Bug Hunter (Gemini 2.5 Pro) - ... ### ✨ DX Reviewer (DeepSeek) - ... ### 🔍 Consolidated Top Issues 1. ... (mentioned by 2+ reviewers — high confidence) 2. ... ``` ## Cost estimation For a typical 500 LOC PR: - Architect (Sonnet, ~40k in / ~3k out): ~$0.18 - Bug Hunter (Gemini 2.5 Pro, same): ~$0.05 - DX Reviewer (DeepSeek, same): ~$0.003 - Merger (Sonnet, ~15k in / ~2k out): ~$0.08 - **Total: ~$0.31 per PR** For small PRs (100 LOC): ~$0.10. Cheap relative to human time. ## Merger: Validation Pass After collecting findings from all 3 Amigos, the Merger runs a **Validation Pass** before synthesis. For each finding, a lightweight sub-agent checks whether the issue is real and significant in the context of the full diff. ### Confidence Scoring | Score | Meaning | Action | |-------|---------|--------| | ≥ 80 | Real issue, significant | Include in output | | 50–79 | Possible issue, minor | Include as "Note" only | | < 50 | Likely false positive | Discard silently | **Auto-discard without scoring:** - Issues that existed before this PR (not introduced by the diff) - Violations already suppressed in CLAUDE.md - Items a senior engineer would not raise in a real review ## Key learnings - **Multi-agent error amplification**: unstructured multi-agent networks can amplify errors (per Google DeepMind 2025 research). This is why the 3 Amigos run in **isolated** contexts and a separate Merger reconciles them, rather than letting them debate. - **Models disagree — that's the point**: if two reviewers flag the same issue, it's probably real. If only one flags it, treat it as a hint. - **Don't post comments inline**: a single consolidated PR comment is less noisy than 30 inline comments, and easier to archive as a learning signal. ## Related Skills - `architecture-enforcement` — deterministic checks that should run BEFORE the reviewers - `edit-lint-feedback-loop` — catches cheap issues before they reach the reviewers ## Gotchas See `gotchas.md`. --- > Source: [toru-oizumi/claude-harness-engineering](https://github.com/toru-oizumi/claude-harness-engineering) — distributed by [TomeVault](https://tomevault.io).