flint-verify-agent-integrity

flint-verify-agent-integrity is a skill for Claude Code from thefraudfather/flint-plugin. It costs 226 tokens per session (2,466 once invoked), scanned A, original, MIT.

Instructions for checking an AI agent's identity, permission, and integrity before it moves money or makes a paid request. FLINT produces signed evidence that records the verification.

In plain words
What is it for?
Use it before payments, purchases, stablecoin transfers, paid API calls, x402 requests, or other actions that move funds.
Why use it?
An agent's identity alone does not show that it is allowed to make a specific purchase or has not been hijacked during the task.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the flint plugin — 1 skill, 2 MCP servers shipped together

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.

agentmods
npx agentmods add skills/thefraudfather/flint-plugin/verify-agent-integrity
Any agent
npx skills add thefraudfather/flint-plugin --skill verify-agent-integrity
Clone the repo
git clone --depth 1 https://github.com/thefraudfather/flint-plugin

Made for: Claude Code.

Or install flint, the plugin that ships this one along with the rest of its 1 skill, 2 MCP servers.

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 flint-verify-agent-integrity

README.md
[![agentmods](https://agentmods.dev/badge/skills/thefraudfather/flint-plugin/verify-agent-integrity.svg)](https://agentmods.dev/skills/thefraudfather/flint-plugin/verify-agent-integrity)
Your own site
<a href="https://agentmods.dev/skills/thefraudfather/flint-plugin/verify-agent-integrity"><img src="https://agentmods.dev/badge/skills/thefraudfather/flint-plugin/verify-agent-integrity.svg" alt="Measured on agentmods" height="20"></a>
Per session 226 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,466 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00226 $0.02466
Opus 5 $0.00113 $0.01233
Sonnet 5 $0.00045 $0.00493
Haiku 4.5 $0.00023 $0.00247

Measured 5d ago against content hash 98e663087995, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

flint-verify-agent-integrity 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 5d 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/verify-agent-integrity/SKILL.md · 180 lines

How it starts

The opening of the file, as written. The whole thing — 180 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FLINT: Verify Agent Integrity Before Payment

What this is for

AI agents are being handed spending authority across payment and stablecoin rails. The existing fraud stack was built for humans and degrades when an agent, rather than a person, is the one transacting. Inside a single organization, identity is largely solved (SPIFFE issues workload identity, A2A signs agent cards, the platform governs its own agents). None of that travels across an organizational boundary: when an agent shows up at a merchant or API the issuer is not a party to, the counterparty has no way to know the agent is who it claims, is allowed to make this purchase, and has not been hijacked mid-task.

FLINT is the layer that answers those questions at transaction time. This skill teaches you to use FLINT's verify-before-pay loop on your own, at the moment an agent is about to move value, so the agent can be trusted to transact and a signed evidence trail exists if anything is later disputed.

The distinction that matters: identity answers who the agent is, FLINT also answers is it authorized for this action and is it still uncompromised. Those last two are the integrity question, and they are what protects the user from an agent that has been taken over, diverted to a new payee, or impersonated.

FLINT is rail-neutral. It verifies the agent; it does not move the money. The payment rail (card, stablecoin, x402, ACH) still executes the transfer. FLINT sits in front of it and decides whether the transfer should proceed.

How agents get compromised (why this matters)

The unsettling part is that a compromised agent usually looks fine. Identity checks still say "yes, this is agent X." A few real patterns this verify-before-pay check is built to catch:

  • Diversion by injected instruction. An agent reads a web page, email, invoice, or tool result that carries hidden instructions, and follows them, quietly changing the payee or redirecting a legitimate payment to an attacker's wallet. The agent passes every health check; its behavior simply drifted. The payment looks routine unless something verifies the action against the agent's declared authority before it executes. FLINT's integrity check plus a declared scope catches a payment that no longer matches what the agent was authorized to do.

Read the full file on GitHub · 180 lines

Files

What ships with it

1 file 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.

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. 5d ago First seen · 180 lines · 226 tokens per session scan A 98e663087995

Subscribe to this mod's changes

flint-verify-agent-integrity is a skill published in the GitHub repository thefraudfather/flint-plugin (0 stars, last pushed 2mo ago), licensed MIT. It adds 226 tokens to every session and 2,466 once invoked, about $0.0011 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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