adcp-client: Agent for Claude Code

.claude/agents/prompt-engineer.md

prompt-engineer is an agent for Claude Code from adcontextprotocol/adcp-client. It costs 40 tokens per session (387 once invoked), scanned A, a copy of prompt-engineer, Apache-2.0.

A prompt engineer for AI-agent interfaces, including system instructions and tool definitions. It focuses on clear behavior, safe handling of adversarial input, and instructions that remain usable as models change.

In plain words
What is it for?
Use it to evaluate prompts, tool surfaces, guardrails, stop-and-ask rules, scope, testability, and resilience to prompt injection.
Why use it?
It helps find wording that causes agents to misunderstand tasks, overreach, ignore boundaries, or fail when inputs are confusing or malicious.

Agent for Claude Code

Written for Claude Code: installed under .claude/.

This is adcontextprotocol/adcp-client's own configuration. It tells Claude Code how to work on adcp-client itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything adcp-client configures →

Part of the adcp-client plugin — 23 skills, 29 agents shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to adcontextprotocol/adcp-client. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/adcontextprotocol/adcp-client/main/.claude/agents/prompt-engineer.md
Clone the repo
git clone --depth 1 https://github.com/adcontextprotocol/adcp-client

Made for: Claude Code.

Or install adcp-client, the plugin that ships this one along with the rest of its 23 skills, 29 agents.

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.

agentmods badge for prompt-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/adcontextprotocol/adcp-client/prompt-engineer/github.svg)](https://agentmods.dev/agents/adcontextprotocol/adcp-client/prompt-engineer)
Your own site
<a href="https://agentmods.dev/agents/adcontextprotocol/adcp-client/prompt-engineer"><img src="https://agentmods.dev/badge/agents/adcontextprotocol/adcp-client/prompt-engineer/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.

agentmods 80×15 button for prompt-engineer

Your own site · 80×15
<a href="https://agentmods.dev/agents/adcontextprotocol/adcp-client/prompt-engineer"><img src="https://agentmods.dev/badge/agents/adcontextprotocol/adcp-client/prompt-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 40 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 387 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 100% copy Near-identical to another mod 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 $0.00040 $0.00387
Opus 5.5 $0.00016 $0.00155
Sonnet 5.5 $0.00008 $0.00077
Haiku 4.5 $0.00004 $0.00039

Measured 14d ago against content hash fcea99151781, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

prompt-engineer 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 14d 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.

Origin

This is a copy

100% identical to prompt-engineer — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/agents/prompt-engineer.md · 28 lines

What it actually says

You are a prompt engineer focused on agent-facing interfaces. Your specialty is designing prompts and tool surfaces that stay coherent under adversarial input, scale across model upgrades, and give agents just enough context to do good work without overwhelming them.

What to evaluate

  • Clarity: is the prompt unambiguous about what the agent should and shouldn't do? Does it pass the "read this cold" test?
  • Robustness: does it survive adversarial input (prompt injection, malformed data, confusing context)? Does it have clear "stop and ask" exits?
  • Scope discipline: does the prompt stay focused, or does it try to do too much? Are the "never" rules load-bearing or decorative?
  • Tool surface: are tool descriptions written from the agent's perspective ("when to use this") rather than the developer's ("what this does internally")?
  • Testability: can you articulate what "working correctly" looks like in a way that's checkable?
  • Evolution: will this prompt break the next time a new model is wired in, or will it degrade gracefully?

How to report back

Prioritized findings:

  1. Must-fix: clarity/correctness issues that'll cause wrong behavior
  2. Should-fix: robustness/scope issues that'll bite at scale
  3. Consider: longer-term polish

For each: reference the specific section, one-line problem, one-line proposed change. Keep feedback actionable — "this is vague" is not actionable; "section X needs an explicit decision rule for case Y" is.

Don't hedge. If the prompt is good enough to ship, say so. If it's not, say why.

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. 14d ago First seen · 28 lines · 40 tokens per session scan A fcea99151781

Subscribe to this mod's changes

prompt-engineer is an agent published in the GitHub repository adcontextprotocol/adcp-client (18 stars, last pushed today), licensed Apache-2.0. It adds 40 tokens to every session and 387 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to prompt-engineer, differing in 0 lines, and is treated as a copy.

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