second-thought

second-thought is a skill for Claude Code, Codex from gg-mo/second-thought-agent-skill. It costs 49 tokens per session (691 once invoked), scanned A, original, MIT.

A decision checkpoint that reviews an agent's proposed idea, plan, design, response, or action against the original request before it is accepted.

In plain words
What is it for?
It helps critique proposals, identify assumptions and risks, compare better options, and recommend whether to proceed, revise, or ask the user.
Why use it?
It helps catch goal drift, weak assumptions, and overlooked concerns while there is still time to change direction.

Skill for Claude CodeCodex

Part of the second-thought plugin — 2 skills, 1 command, 1 hook shipped together

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 skills/gg-mo/second-thought-agent-skill/second-thought
Any agent
npx skills add gg-mo/second-thought-agent-skill --skill second-thought
Clone the repo
git clone --depth 1 https://github.com/gg-mo/second-thought-agent-skill

Made for: Claude Code, Codex.

Or install second-thought, the plugin that ships this one along with the rest of its 2 skills, 1 command, 1 hook.

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 second-thought

README.md
[![agentmods](https://agentmods.dev/badge/skills/gg-mo/second-thought-agent-skill/second-thought.svg)](https://agentmods.dev/skills/gg-mo/second-thought-agent-skill/second-thought)
Your own site
<a href="https://agentmods.dev/skills/gg-mo/second-thought-agent-skill/second-thought"><img src="https://agentmods.dev/badge/skills/gg-mo/second-thought-agent-skill/second-thought.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 691 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 $0.00049 $0.00691
Opus 5 $0.00024 $0.00345
Sonnet 5 $0.00010 $0.00138
Haiku 4.5 $0.00005 $0.00069

Measured 4d ago against content hash 09b914829abf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

second-thought 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.

skills/second-thought/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Second Thought

A standalone decision checkpoint engine that asks whether the current direction is actually right before the agent commits.

Core rule

Before moving forward with a meaningful proposal, run a critique against the original intent, not just the latest turn.

Default behavior: auto-build the payload from conversation context. Do not require manual field entry unless the user explicitly wants manual/debug mode.

Input contract

Provide these fields to the critique engine:

  • original_intent
  • current_context
  • proposal_type (idea | decision | design | plan | action | tool_call | response)
  • proposal
  • rationale
  • constraints
  • risk_level (low | medium | high)
  • stage (brainstorming | convergence | pre_execution | post_feedback)
  • should_challenge

Output contract

Produce this structured result internally:

  • status (proceed | revise | prompt_human)
  • summary
  • goal_alignment
  • concerns
  • assumptions
  • better_options
  • challenge_prompt
  • recommended_next_step
  • prompt_to_human

User-facing response contract

Default output should be human-readable, not raw JSON.

  • Use a conversational response in a few sentences (about 2-4).
  • Avoid rigid section labels like Decision:, Why:, Next: unless explicitly requested.
  • Include the decision (proceed | revise | prompt_human) naturally in prose.
  • Include at least one specific reason grounded in the current proposal/context.
  • Include one concrete next step.
  • If prompt_human, ask exactly one focused clarification question.

Only show full JSON when the human explicitly requests JSON/debug/contract format.

Stage behavior

  • brainstorming: exploratory but critical; do not reward weak framing
  • convergence: skeptical; test if agreement is correctness vs momentum
  • pre_execution: strict; verify reversibility, risk, missing information
  • post_feedback: re-evaluate without overfitting to latest feedback

Decision standard

  • proceed: strong intent alignment, acceptable assumptions, no required human clarification
  • revise: direction is promising but flawed, drifting, or weakly justified
  • prompt_human: ambiguity, under-specification, high impact, irreversibility, or clear preference/judgment call needed

Read the full file on GitHub · 98 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 · 98 lines · 49 tokens per session scan A 09b914829abf

Subscribe to this mod's changes

second-thought is a skill published in the GitHub repository gg-mo/second-thought-agent-skill (5 stars, last pushed 4mo ago), licensed MIT. It adds 49 tokens to every session and 691 once invoked, about $0.0002 per session on Opus 5. 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 2026-08-31.

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