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.
npx agentmods add skills/impactbrussels/founderos/apply-mental-modelsnpx skills add impactbrussels/FounderOS --skill apply-mental-modelsgit clone --depth 1 https://github.com/impactbrussels/FounderOSWrote 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/impactbrussels/founderos/apply-mental-models)<a href="https://agentmods.dev/skills/impactbrussels/founderos/apply-mental-models"><img src="https://agentmods.dev/badge/skills/impactbrussels/founderos/apply-mental-models.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00115 | $0.01048 |
| Opus 5 | $0.00057 | $0.00524 |
| Sonnet 5 | $0.00023 | $0.00210 |
| Haiku 4.5 | $0.00012 | $0.00105 |
Grade A, and why
apply-mental-models 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Apply Mental Models
Founders make a hundred judgement calls with no playbook. The fastest way to think better isn't more data - it's running the decision through a few sharp lenses that each catch a different blind spot. This skill picks the right lenses for your decision and forces the thinking that gut alone skips. Proof before hype: a decision examined from three angles beats a confident first instinct.
The method
Built on the Founder OS scaffold. The full lens library - classic models (Munger, Taleb, Bezos, Thiel, Graham) and the author's frameworks (Proof Ladder, Trust Stack, Narrative-Evidence Gap, Five Killers, Operator's Creed) - is in references/mental-models.md.
Step 1 - Frame the decision
State it in one sentence, and classify it:
- Reversible (two-way door)? Then bias to speed - don't over-think it.
- Irreversible (one-way door)? Slow down; this is where lenses earn their keep.
- What's the
[CONSTRAINT](runway, time) and what would make this decision wrong?
Step 2 - Pick 2-3 lenses that fit (not all of them)
Match the lens to the decision (see references for the full set and when to use each):
| Decision type | Lenses that earn their keep |
|---|---|
| Big bet / strategy | Inversion · Power law · Contrarian question · Barbell |
| Launch / claim / messaging | Proof Ladder · Copy Test · Narrative-Evidence Gap |
| Survival / runway | The Five Killers · Antifragility · Via negativa |
| Build vs not | Work-backwards / press-release test · Do things that don't scale |
| Trust / positioning | Trust Stack · Comparison-Set Problem |
| Advice you've been given | Skin in the game · Circle of competence |
Step 3 - Run the decision through each lens
For each chosen lens, write the one sentence it produces. E.g. Inversion: "the surest way to kill this is X - so guard against X." Power law: "one of these five things matters most - it's Y."
Step 4 - Read the pattern
What ships with it
1 file 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.
- 5d ago First seen · 91 lines · 115 tokens per session scan A 9b4ca586530a
apply-mental-models is a skill published in the GitHub repository impactbrussels/FounderOS (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 115 tokens to every session and 1,048 once invoked, about $0.0006 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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