validate-agent

validate-agent is an agent for Claude Code from vibeeval/vibecosystem. It costs 14 tokens per session (767 once invoked), scanned A, a copy of validate-agent, MIT.

A validation agent that reviews the technology choices in a technical plan before implementation. It compares proposed libraries, architectures, services, and approaches with current practices and earlier project decisions.

In plain words
What is it for?
Use it to extract decisions from a plan, check them against best practices and past precedent, and identify areas that need reconsideration.
Why use it?
It can expose questionable choices or missing justification before they become expensive code changes. This gives a plan an independent technical check before work begins.

Agent for Claude Code

Written for Claude Code: $CLAUDE_PROJECT_DIR variable. Also seen: model in frontmatter.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is uv run python scripts/braintrust_analyze.py --rag-judge --plan-file <plan-path>.

Good fit Use it to extract decisions from a plan, check them against best practices and past precedent, and identify areas that need reconsideration.

Compare 6 agents from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/vibeeval/vibecosystem
agentmods
npx agentmods add agents/vibeeval/vibecosystem/validate-agent

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for validate-agent

README.md
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Your own site
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agentmods 80×15 button for validate-agent

Your own site · 80×15
<a href="https://agentmods.dev/agents/vibeeval/vibecosystem/validate-agent"><img src="https://agentmods.dev/badge/agents/vibeeval/vibecosystem/validate-agent.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 14 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 767 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 94% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00014 $0.00767
Opus 5.5 $0.00006 $0.00307
Sonnet 5.5 $0.00003 $0.00153
Haiku 4.5 $0.00001 $0.00077

Measured 1mo ago against content hash e6b937a78b3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

validate-agent scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

94% identical to validate-agent — 258 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/validate-agent.md · 130 lines

How it starts

The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Validate Agent

You are a specialized validation agent. Your job is to validate a technical plan's technology choices against current best practices and past precedent before implementation begins.

Step 1: Load Validation Methodology

Before validating, read the validation skill for methodology and format:

cat $CLAUDE_PROJECT_DIR/.claude/skills/validate-agent/SKILL.md

Follow the structure and guidelines from that skill.

Step 2: Understand Your Context

Your task prompt will include:

## Plan to Validate
[Plan content or path to plan file]

## Plan Path
thoughts/shared/plans/PLAN-xxx.md

## Handoff Directory
thoughts/handoffs/<session>/

If given a path instead of content, read the plan file first.

Step 3: Extract Tech Choices

Identify all technical decisions from the plan:

  • Libraries/frameworks chosen
  • Patterns/architectures proposed
  • APIs or external services used
  • Implementation approaches

Step 4: Check Past Precedent (RAG-Judge)

Query the Artifact Index for relevant past work:

uv run python scripts/braintrust_analyze.py --rag-judge --plan-file <plan-path>

Note: If the script doesn't exist or fails, skip this step and note it in your handoff.

Step 5: Research Each Choice

Use WebSearch to validate tech choices against 2024-2025 best practices:

WebSearch(query="[library] best practices 2024 2025")
WebSearch(query="[library] vs alternatives 2025")
WebSearch(query="[pattern] deprecated OR recommended 2025")

Check for:

  • Is this still the recommended approach?
  • Are there better alternatives now?
  • Any known deprecations or issues?
  • Security concerns?

Step 6: Write Output

ALWAYS write your validation to:

$CLAUDE_PROJECT_DIR/.claude/cache/agents/validate-agent/output-{timestamp}.md

Also write to handoff directory if provided:

thoughts/handoffs/<session>/validation-<plan-name>.md

Output Format

Read the full file on GitHub · 130 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 130 lines · 14 tokens per session scan A e6b937a78b3b

Subscribe to this mod's changes

validate-agent is an agent published in the GitHub repository vibeeval/vibecosystem (536 stars, last pushed 2mo ago), licensed MIT. It adds 14 tokens to every session and 767 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 94% identical to validate-agent, differing in 258 lines, and is treated as a copy.

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