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 kingoo123/agent-harness-skills --skill tool-contract-designergit clone --depth 1 https://github.com/kingoo123/agent-harness-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/kingoo123/agent-harness-skills/tool-contract-designer)<a href="https://agentmods.dev/skills/kingoo123/agent-harness-skills/tool-contract-designer"><img src="https://agentmods.dev/badge/skills/kingoo123/agent-harness-skills/tool-contract-designer/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/kingoo123/agent-harness-skills/tool-contract-designer"><img src="https://agentmods.dev/badge/skills/kingoo123/agent-harness-skills/tool-contract-designer.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 | $0.00038 | $0.00198 |
| Opus 5 | $0.00019 | $0.00099 |
| Sonnet 5 | $0.00008 | $0.00040 |
| Haiku 4.5 | $0.00004 | $0.00020 |
Grade A, and why
tool-contract-designer 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 11d 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.
What it actually says
Tool Contract Designer
Goal
Make tool use explicit, typed, auditable, and safe.
Workflow
For each tool:
- Define the tool's single responsibility.
- Define input schema.
- Define output schema.
- Define permission level.
- Define approval requirements.
- Define failure modes.
- Define retry policy.
- Define audit log.
Permission levels
read_only
edit_safe
execute_safe
network_safe
admin
Output
tool:
name:
purpose:
input_schema:
output_schema:
permission_level:
requires_approval:
failure_modes:
retry_policy:
audit_log:
examples:
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.
- 11d ago First seen · 51 lines · 38 tokens per session scan A 265c1d9b142a
tool-contract-designer is a skill published in the GitHub repository kingoo123/agent-harness-skills (2 stars, last pushed 3mo ago), licensed MIT. It adds 38 tokens to every session and 198 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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