Borrowing it
Nothing to install: this file belongs to mishahanin/heading-os. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mishahanin/heading-os/main/.claude/skills/deep-think/SKILL.mdgit clone --depth 1 https://github.com/mishahanin/heading-osWrote 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.
[](https://agentmods.dev/skills/mishahanin/heading-os/deep-think)<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="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00178 | $0.02710 |
| Opus 5 | $0.00089 | $0.01355 |
| Sonnet 5 | $0.00036 | $0.00542 |
| Haiku 4.5 | $0.00018 | $0.00271 |
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 8d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- deep-think — 89% identical, 8 lines differ
How it starts
The opening of the file, as written. The whole thing — 263 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 throughdepth(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:
-
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."
-
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?"
-
Contradictory signals -- Information contains tension or paradox. Example: Pipeline shows strong momentum but CRM health shows RED contacts on key relationships.
-
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?"
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.
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.
- 8d ago First seen · 263 lines · 178 tokens per session scan A 47b564204aed
deep-think is a skill published in the GitHub repository mishahanin/heading-os (11 stars, last pushed yesterday), licensed Apache-2.0. It adds 178 tokens to every session and 2,710 once invoked, about $0.0009 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 2026-08-30.
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