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 skills add mthines/agent-skills --skill behavioral-designgit clone --depth 1 https://github.com/mthines/agent-skillsWrote 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/mthines/agent-skills/behavioral-design)<a href="https://agentmods.dev/skills/mthines/agent-skills/behavioral-design"><img src="https://agentmods.dev/badge/skills/mthines/agent-skills/behavioral-design/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.
<a href="https://agentmods.dev/skills/mthines/agent-skills/behavioral-design"><img src="https://agentmods.dev/badge/skills/mthines/agent-skills/behavioral-design.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00179 | $0.01665 |
| Opus 5.5 | $0.00072 | $0.00666 |
| Sonnet 5.5 | $0.00036 | $0.00333 |
| Haiku 4.5 | $0.00018 | $0.00167 |
Grade A, and why
behavioral-design 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 16d 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 — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Behavioral Design
Make the target behavior the path of least resistance, then prove it moved. Advisory only: this skill writes plans, outlines, and reports, never product code.
Mode Detection
Parse the first token of $ARGUMENTS.
| Mode | Trigger | Output |
|---|---|---|
diagnose |
"why don't / aren't people…", "what's blocking adoption", first token diagnose |
Barrier diagnosis (templates/intervention-plan.md § Diagnosis only) |
design |
"how do we get people to…", "how do we fix this", "nudge", "drive adoption", the user proposes specific levers to apply ("can we auto-enroll…"), first token design |
Full intervention plan (templates/intervention-plan.md) |
workshop |
"workshop", "presentation", "talk", "session for the team", first token workshop |
Workshop plan (templates/workshop.md) |
review |
"review this rollout / plan / flow" for an existing written plan or shipped flow, first token review |
Findings against the rules, ranked |
No mode token and no matching phrase → design (it includes the diagnosis).
State the detected mode and the target behavior in one line before continuing:
Mode: design
Target behavior: engineers run `pnpm test` locally before pushing
Required Reading by Mode
Load on demand — never all up-front.
| Mode | Load |
|---|---|
diagnose |
rules/diagnosis.md, rules/dual-process.md |
design |
rules/diagnosis.md, rules/interventions.md, rules/dual-process.md, rules/ethics.md, references/frameworks.md § Evidence grading |
workshop |
rules/workshop.md, rules/dual-process.md, rules/ethics.md |
review |
rules/dual-process.md, rules/interventions.md, rules/ethics.md, references/frameworks.md § Evidence grading |
What ships with it
10 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.
- 16d ago First seen · 121 lines · 179 tokens per session scan A f0ed6d09d99f
behavioral-design is a skill published in the GitHub repository mthines/agent-skills (19 stars, last pushed today), licensed MIT. It adds 179 tokens to every session and 1,665 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 2026-10-03.
Other skills, from other repositories
source-driven-development
Grounds framework-specific code decisions in official documentation instead of training data or memory. Use before writing framework- or library-specific code (forms, routing, data fetching, auth, state management), when the user asks for "current best practices" or "documented"/"verified" code, or before reviewing…
hidden-talents
Interview you in depth to surface overlooked or suppressed talents and write your Personal Talent Manual.
deconstruct
Reverse-engineer why a finished piece of work succeeds and extract what transfers to your own — rules, a checklist, and a first exercise.
socratic
Diagnose a confusion Socratically, one question at a time, until the question actually worth answering surfaces — then answer that one.
two-layer-explain
Explain a concept twice — for a newcomer and for an expert — then bridge the two layers, flag the likely misunderstandings, and set three check questions.
creating-explainers
Use when creating an interactive explainer - a single self-contained HTML page with hand-built Canvas figures. Handles source-file explainers, topic-driven research explainers, and mixed intake where files provide the spine and research adds support. Trigger phrases include "make an explainer", "turn this paper into…