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 AnastasiyaW/codex-claude-code-config --skill agent-harness-designgit clone --depth 1 https://github.com/AnastasiyaW/codex-claude-code-configWrote 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/anastasiyaw/codex-claude-code-config/agent-harness-design)<a href="https://agentmods.dev/skills/anastasiyaw/codex-claude-code-config/agent-harness-design"><img src="https://agentmods.dev/badge/skills/anastasiyaw/codex-claude-code-config/agent-harness-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/anastasiyaw/codex-claude-code-config/agent-harness-design"><img src="https://agentmods.dev/badge/skills/anastasiyaw/codex-claude-code-config/agent-harness-design.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00195 | $0.00668 |
| Opus 5 | $0.00097 | $0.00334 |
| Sonnet 5 | $0.00039 | $0.00134 |
| Haiku 4.5 | $0.00019 | $0.00067 |
Grade A, and why
agent-harness-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 9d 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
Agent Harness Design
Eleven operational reference sheets for designing a safe, observable agent harness. They are situational — load only the one(s) relevant to the current task from references/ (this is why they live in a skill rather than always-on rules: building an agent harness is occasional, so the detail should not bloat every session's context).
references/agent-tool-design.md— 15-class risk taxonomy, 7-type permission decision object, draft/commit naming, structured tool results, deferred tool loading, hosted vs client tools, connector code-execution pattern.references/context-trust-labels.md— trusted / semi_trusted / untrusted labels + verbatim boundary statement; prompt-injection defense.references/agent-budgets.md— 10 mandatory budget types every agent loop must declare.references/agent-evals.md— 13 eval categories + 13 adversarial test cases + when to add regression evals.references/agent-observability.md— 16 trace fields per model call, 7-question audit, 6-step incident response.references/agentic-rag-model-policy.md— self-improving agentic RAG state, specialist roles, evaluation vectors, Pareto selection, OpenAI model/effort policy, and Programmatic Tool Calling adoption gates.references/agent-plan-artifact.md— planning mode, plan artifact format (10 fields), plan-validate-execute.references/agent-approval-records.md— approval request/result JSON schemas, scope/expiration, no self-approval.references/agent-streaming.md— buffering for incremental tool calls when stream=True; abort handling; output guardrail modes.references/agent-event-model.md— 13 typed events for harness state persistence (replay/audit/compaction/evals).references/agent-skill-install-checklist.md— pre/during/post install + audit + incident response for 3rd-party skills.
Source: distilled from the agents-best-practices skill (Denis Sergeevitch, MIT) + Anthropic harness-design engineering. Read the specific reference before applying — do not work from this index alone.
What ships with it
11 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.
- references/agent-approval-records.md 6.4 KB
- references/agent-budgets.md 6.3 KB
- references/agent-evals.md 7.5 KB
- references/agent-event-model.md 7.3 KB
- references/agent-observability.md 6.5 KB
- references/agent-plan-artifact.md 7.2 KB
- references/agent-skill-install-checklist.md 15 KB
- references/agent-streaming.md 6.7 KB
- references/agent-tool-design.md 17 KB
- references/agentic-rag-model-policy.md 7.8 KB
- references/context-trust-labels.md 9.2 KB
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.
- 9d ago First seen · 23 lines · 195 tokens per session scan A 3ba138d64b5f
agent-harness-design is a skill published in the GitHub repository AnastasiyaW/codex-claude-code-config (149 stars, last pushed today), licensed MIT. It adds 195 tokens to every session and 668 once invoked, about $0.0010 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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