using-second-thought

using-second-thought is a skill for Claude Code, Codex from gg-mo/second-thought-agent-skill. It costs 39 tokens per session (486 once invoked), scanned A, original, MIT.

Instructions that make the Second Thought review run automatically before major decisions or costly actions.

In plain words
What is it for?
They help agents check plans and actions before committing, while allowing a user to intentionally skip one review with a stated reason.
Why use it?
They add a review step before edits, migrations, deployments, publishing, or other actions that may be hard to undo.

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/using-second-thought
Any agent
npx skills add gg-mo/second-thought-agent-skill --skill using-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.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 486 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 $0.00039 $0.00486
Opus 5 $0.00019 $0.00243
Sonnet 5 $0.00008 $0.00097
Haiku 4.5 $0.00004 $0.00049

Measured 3d ago against content hash 5660c926e796, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

using-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 3d 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/using-second-thought/SKILL.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Using Second Thought

Rule

Before a major direction is accepted, run second-thought critique automatically.

Major direction includes:

  • finalizing a design/plan
  • taking a meaningful tool call or action
  • committing to an execution path that is costly or hard to reverse

Hybrid Trigger Model

Use a hybrid model:

  1. Automatic gate at high-commitment moments.
  2. Manual invocation available at any time.

Automatic gate should trigger when requests involve:

  • committing/merging/shipping/deploying/publishing
  • meaningful file edits, deletions, migrations, or refactors
  • potentially destructive or irreversible actions
  • high-cost, high-blast-radius, or under-specified execution steps

If a platform supports runtime message transforms or pre-action hooks, use those to trigger the gate automatically. If not, enforce this via startup instructions and agent process discipline.

Escape Hatch

Allow one-shot bypass when speed is intentionally prioritized:

  • User can include [st:skip <reason>] or #st-skip.
  • Agent should acknowledge the bypass reason explicitly.
  • Bypass should not become default behavior.

Priority

  1. User instructions
  2. Second Thought skills
  3. Default behavior

How to use

  1. Capture/infer original_intent.
  2. Summarize/infer current_context.
  3. Build critique payload automatically.
  4. Run the critique engine.
  5. Follow status strictly:
  • proceed -> continue with checkpoint discipline
  • revise -> improve proposal and rerun critique
  • prompt_human -> ask prompt_to_human before continuing
  1. Present results in conversational human language by default (few sentences); keep raw JSON internal unless explicitly requested.

Platform mapping

If skill/tool names differ by platform, use the mapped equivalents in references/:

  • codex-tools.md
  • copilot-tools.md
  • gemini-tools.md

Anti-patterns

  • treating agreement as proof
  • validating the latest suggestion without checking original intent
  • pushing forward with high-impact ambiguity
  • giving generic caution without actionable guidance

Read the full file on GitHub · 75 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago First seen · 75 lines · 39 tokens per session scan A 5660c926e796

Subscribe to this mod's changes

using-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 39 tokens to every session and 486 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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