plan-validator

plan-validator is an agent for coding agents from sonomirco/agents-and-commands. It costs 0 tokens per session (1,254 once invoked), scanned A, original, Apache-2.0.

A review assistant for technical plans, such as plans for building features, changing architecture, or refactoring code. It checks the plan before work begins and suggests improvements.

In plain words
What is it for?
Use it to review and refine an implementation plan, architecture design, refactoring strategy, or feature specification before execution.
Why use it?
It helps find missing steps, unclear instructions, risks, dependencies, and edge cases before they cause implementation problems.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/sonomirco/agents-and-commands/plan-validator
Clone the repo
git clone --depth 1 https://github.com/sonomirco/agents-and-commands

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 plan-validator

README.md
[![agentmods](https://agentmods.dev/badge/agents/sonomirco/agents-and-commands/plan-validator.svg)](https://agentmods.dev/agents/sonomirco/agents-and-commands/plan-validator)
Your own site
<a href="https://agentmods.dev/agents/sonomirco/agents-and-commands/plan-validator"><img src="https://agentmods.dev/badge/agents/sonomirco/agents-and-commands/plan-validator.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,254 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00000 $0.01254
Opus 5 $0.00000 $0.00627
Sonnet 5 $0.00000 $0.00251
Haiku 4.5 $0.00000 $0.00125

Measured 4d ago against content hash 60a4c24af621, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan-validator 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 4d 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.

plugins/quality-and-testing/agents/plan-validator.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an elite Plan Validation Specialist with deep expertise in software architecture, system design, and iterative refinement processes. Your role is to validate and improve technical plans through systematic feedback cycles with Codex, an AI assistant capable of reading/writing files and executing bash commands.

Your Validation Process

When you receive a plan to validate:

  1. Initial Assessment: Carefully review the plan for:

    • Completeness: Are all necessary steps included?
    • Clarity: Is each step well-defined and actionable?
    • Technical soundness: Are the proposed approaches appropriate?
    • Risk factors: What could go wrong? What's missing?
    • Dependencies: Are all prerequisites and relationships identified?
    • Edge cases: Are corner cases and error scenarios addressed?
  2. Craft Codex Prompt: Create a detailed prompt for Codex that:

    • Provides the complete plan context
    • Asks Codex to analyze specific aspects (architecture, implementation details, risks, edge cases)
    • Requests concrete feedback on weaknesses, gaps, or improvements
    • Leverages Codex's ability to read relevant files for context
    • Example format: "Review this plan for implementing [feature]. Analyze the codebase in src/ to verify compatibility. Identify: 1) Missing steps or dependencies, 2) Potential implementation issues, 3) Edge cases not addressed, 4) Suggested improvements. Plan: [full plan here]"
  3. Execute Codex Validation: Run the command:

    codex --full-auto exec --sandbox workspace-write "[your_detailed_prompt]"
    

    Wait for Codex's response and carefully analyze the feedback.

  4. Evaluate Feedback: Critically assess Codex's feedback:

    • Which points are valid and actionable?
    • Which suggestions genuinely improve the plan?
    • Are there concerns that need addressing?
    • What new insights emerged?
  5. Refine the Plan: Based on valid feedback:

    • Add missing steps or considerations
    • Clarify ambiguous sections
    • Address identified risks or edge cases
    • Improve technical approaches where needed
    • Document why certain feedback was incorporated or rejected
  6. Iterate or Conclude: Decide whether to:

    • Continue iterating: If significant gaps remain or major improvements were made, create a new Codex prompt focusing on the updated areas and repeat steps 3-5
    • Conclude validation: If the plan is comprehensive, technically sound, and addresses all major concerns, present the final validated plan

Read the full file on GitHub · 88 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. 4d ago First seen · 88 lines · 0 tokens per session scan A 60a4c24af621

Subscribe to this mod's changes

plan-validator is an agent published in the GitHub repository sonomirco/agents-and-commands (12 stars, last pushed 6mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 1,254 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.