agent-system-prompt-architect

agent-system-prompt-architect is a skill for Codex from CR-730/agent-system-prompt-architect-skill. It costs 55 tokens per session (2,927 once invoked), scanned A, original, MIT.

A workflow for designing and reviewing system prompts that control how another AI agent behaves.

In plain words
What is it for?
It helps create deployable prompts for agent projects and revise them into compact, runtime-ready instructions.
Why use it?
It turns incomplete requirements into clearer instructions covering the agent's role, boundaries, tools, evidence, output format, and safety behavior.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit It helps create deployable prompts for agent projects and revise them into compact, runtime-ready instructions.

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Install with agentmods
npx agentmods add skills/cr-730/agent-system-prompt-architect-skill/agent-system-prompt-architect
Install

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.

Any agent
npx skills add CR-730/agent-system-prompt-architect-skill --skill agent-system-prompt-architect
Clone the repo
git clone --depth 1 https://github.com/CR-730/agent-system-prompt-architect-skill

Made for: Codex.

Wrote 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.

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README.md
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Your own site
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agentmods 80×15 button for agent-system-prompt-architect

Your own site · 80×15
<a href="https://agentmods.dev/skills/cr-730/agent-system-prompt-architect-skill/agent-system-prompt-architect"><img src="https://agentmods.dev/badge/skills/cr-730/agent-system-prompt-architect-skill/agent-system-prompt-architect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,927 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00055 $0.02927
Opus 5 $0.00028 $0.01463
Sonnet 5 $0.00011 $0.00585
Haiku 4.5 $0.00006 $0.00293

Measured 12d ago against content hash 6e1670e1ace8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

agent-system-prompt-architect 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 12d 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.

skills/agent-system-prompt-architect/SKILL.md · 178 lines

How it starts

The opening of the file, as written. The whole thing — 178 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent System Prompt Architect

Goal

Turn partial agent requirements into a deployable system prompt for another agent project.

Your entire response is the deployable prompt by default. No preamble, no postscript, no design rationale, no recap of what you changed, no "设计说明 / for-your-review / non-deployable" appendix. Everything you want the user to see goes inside the prompt itself — as a section header, comment, or labeled assumption — not in a separate commentary block. Switch out of this default only when the user explicitly asks for review, explanation, or design notes; in that case label any non-prompt section clearly so the deployable prompt is still identifiable.

The runtime-isolation rules in Prompt vs runtime separation apply to the entire response, not just the prompt body. Code names, schema field names, and pipeline labels you saw in the user's request must be gone from anything you output unless the runtime keys on those exact strings.

Draft in the same turn. Ask one clarifying question only when, after reading the request, you still cannot name the agent's domain and primary task — for example, a bare schema with no hint of who uses the agent or what they need from it. Naming a brand, codename, user group, or task is enough to start drafting; missing samples, edge cases, or tool specs are handled with labeled assumptions inside the draft.

When you do have to ask, request the smallest pair that unblocks drafting: one concrete sample input the agent would actually receive, plus what the user wants the agent to return for that input. A real example surfaces the agent's job faster than a discovery interview.

Read order

  1. Read references/prompt-engineering-principles.md first as the baseline writing checklist.
  2. Identify the target agent's role, users, tasks, tools, boundaries, output style, safety needs, and deployment constraints from the request.
  3. Resolve missing information by labeling assumptions inline in the draft. Make assumptions visible (e.g., a short "Assumptions" line under Inputs or Output contract) so the user can correct them in the next turn instead of in a clarification round-trip. The clarification exception in the Goal applies only when domain and primary task are both unidentifiable.
  4. Preserve explicit user requirements over defaults.
  5. Match the user's requested or implied language for the generated prompt, section names, labels, examples, and templates. Internal skill notes may stay in English.
  6. Load a reference file only when it would change the prompt: references/prompt-techniques.md for reasoning, planning, tool, retrieval, reliability, or format-stability decisions; references/domain-adaptation.md for domain gaps that change behavior; and the capability module that matches the target agent's needed behavior.

Read the full file on GitHub · 178 lines

Changes

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.

  1. 12d ago First seen · 178 lines · 55 tokens per session scan A 6e1670e1ace8

Subscribe to this mod's changes

agent-system-prompt-architect is a skill published in the GitHub repository CR-730/agent-system-prompt-architect-skill (20 stars, last pushed 3mo ago), licensed MIT. It adds 55 tokens to every session and 2,927 once invoked, about $0.0003 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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