poc-builder

poc-builder is an agent for Claude Code from trailofbits/skills. It costs 46 tokens per session (1,557 once invoked), scanned A, original, CC-BY-SA-4.0.

A security agent that creates proof-of-concept exploits and tests for a confirmed vulnerability, including examples that should fail when required conditions are missing.

In plain words
What is it for?
It is for writing exploit pseudocode, runnable exploit examples, unit tests, and negative tests for vulnerability verification.
Why use it?
It turns a verified security finding into a reproducible demonstration and documents when exploitation is not possible.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the fp-check plugin — 1 skill, 3 agents shipped together

Good fit It is for writing exploit pseudocode, runnable exploit examples, unit tests, and negative tests for vulnerability verification.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/trailofbits/skills/poc-builder
About the project

Trail of Bits Skills Marketplace is a collection of Claude Code plugins, skills, agents, commands, and instructions for security analysis, vulnerability detection, code auditing, and development workflows. It is for developers and security researchers using AI-assisted tools to inspect software, smart contracts, CI workflows, and related artifacts. The catalogue entries are examples of the marketplace’s reusable agent extensions.

trailofbits/skills · 6,988 stars · on GitHub

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.

Clone the repo
git clone --depth 1 https://github.com/trailofbits/skills

Made for: Claude Code.

Or install fp-check, the plugin that ships this one along with the rest of its 1 skill, 3 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 poc-builder

README.md
[![agentmods](https://agentmods.dev/badge/agents/trailofbits/skills/poc-builder.svg)](https://agentmods.dev/agents/trailofbits/skills/poc-builder)
Your own site
<a href="https://agentmods.dev/agents/trailofbits/skills/poc-builder"><img src="https://agentmods.dev/badge/agents/trailofbits/skills/poc-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 46 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,557 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 unknown 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 $0.00046 $0.01557
Opus 5 $0.00023 $0.00779
Sonnet 5 $0.00009 $0.00311
Haiku 4.5 $0.00005 $0.00156

Measured 4d ago against content hash 236188b68227, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

poc-builder 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 4d 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.

plugins/fp-check/agents/poc-builder.md · 174 lines

The source is not reproduced here

Licensed CC-BY-SA-4.0

The repository is licensed CC-BY-SA-4.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 4d ago First seen · 174 lines · 46 tokens per session scan A 236188b68227

Subscribe to this mod's changes

poc-builder is an agent published in the GitHub repository trailofbits/skills (6,988 stars, last pushed 4d ago), licensed CC-BY-SA-4.0. It adds 46 tokens to every session and 1,557 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 2026-09-03.

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