deep-think

deep-think is a skill for Claude Code from mishahanin/heading-os. It costs 178 tokens per session (2,725 once invoked), scanned A, original, Apache-2.0.

A step-by-step reasoning skill for difficult questions, decisions, and plans with several connected factors. It records assumptions, possible paths, revisions, and the basis for its recommendation.

In plain words
What is it for?
Use it for complex decisions, strategy questions, and problems that need several reasoning steps. You can choose a quick, standard, or deep level of analysis and provide extra context.
Why use it?
It makes the reasoning easier to inspect and challenge when the answer is uncertain or involves trade-offs. This reduces the chance of hiding an important assumption or skipping an alternative.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths.

Good fit Use it for complex decisions, strategy questions, and problems that need several reasoning steps. You can choose a quick, standard, or deep level of analysis and provide extra context.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mishahanin/heading-os/deep-think
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.

Any agent
npx skills add mishahanin/heading-os --skill deep-think
Clone the repo
git clone --depth 1 https://github.com/mishahanin/heading-os

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 deep-think

README.md
[![agentmods](https://agentmods.dev/badge/skills/mishahanin/heading-os/deep-think/github.svg)](https://agentmods.dev/skills/mishahanin/heading-os/deep-think)
Your own site
<a href="https://agentmods.dev/skills/mishahanin/heading-os/deep-think"><img src="https://agentmods.dev/badge/skills/mishahanin/heading-os/deep-think/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for deep-think

Your own site · 80×15
<a href="https://agentmods.dev/skills/mishahanin/heading-os/deep-think"><img src="https://agentmods.dev/badge/skills/mishahanin/heading-os/deep-think.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 178 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,725 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00178 $0.02725
Opus 5.5 $0.00071 $0.01090
Sonnet 5.5 $0.00036 $0.00545
Haiku 4.5 $0.00018 $0.00272

Measured 1mo ago against content hash c7d2e7765e0c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

deep-think 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

Copies of this mod

1 near-identical copy found in the catalogue:

.claude/skills/deep-think/SKILL.md · 264 lines

How it starts

The opening of the file, as written. The whole thing — 264 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Deep Think

Structured sequential reasoning engine. Breaks complex problems into visible, numbered thought steps -- with revision, branching, and maritime-framed recommendations. Every assumption surfaced. Every path explored. Every recommendation backed by the chain of reasoning that produced it.

This skill replaces the Sequential Thinking MCP server. The key improvement: reasoning is visible and challengeable, not hidden inside tool calls.


Variables

  • problem (required) -- The question, decision, or problem to think through
  • depth (optional) -- quick (3-5 steps), standard (6-10 steps, default), deep (10-15+ steps)
  • context (optional) -- Additional context, constraints, or files to reference

Customization (optional, Phase 0)

This skill is customization-aware (pilot). Before reasoning, resolve any per-exec overrides: python scripts/resolve_customization.py --skill .claude/skills/deep-think. Apply any activation_steps_prepend, persistent_facts (facts to always honour, e.g. a preferred default depth or currency), and output-path overrides from the merged result. On any failure, proceed with the defaults below -- never block. Layout + authoring guide: config/skill-custom/README.md.


When to Engage Proactively

Activate this skill WITHOUT being asked when you detect any of these conditions:

  1. Multi-variable decisions -- 3+ competing factors with no obvious weighting. Example: "Should we enter [a new market] through PartnerCo or direct? There's a tender deadline, partner margin question, and a competitive threat."

  2. Strategy under uncertainty -- The answer depends on unknowns or contested assumptions. Example: "How should we price the [target-market] deal given competitive pressure from a state-aligned vendor?"

  3. Contradictory signals -- Information contains tension or paradox. Example: Pipeline shows strong momentum but CRM health shows RED contacts on key relationships.

  4. High-stakes reasoning -- Being wrong is costly: investor positioning, partnership terms, competitive response, market entry timing. Example: "How much technical detail should we share with a potential investor who sits on a competitor's board?"

Read the full file on GitHub · 264 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. 1mo ago Changed c7d2e7765e0c
  2. 1mo ago Changed · +1 lines fb3cc861e83c
  3. 1mo ago First seen · 263 lines · 178 tokens per session scan A 47b564204aed

Subscribe to this mod's changes

deep-think is a skill published in the GitHub repository mishahanin/heading-os (11 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 178 tokens to every session and 2,725 once invoked, about $0.0007 per session on Opus 5.5. 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 2026-08-30.