business-rules-extractor

business-rules-extractor is an agent for Claude Code from ronmkr/PromptBook. It costs 53 tokens per session (502 once invoked), scanned A, a copy of business-rules-extractor, Apache-2.0.

A code-reading assistant that extracts business rules—such as calculations, validations, permissions, and policies—from older software and writes them as Given/When/Then specifications.

In plain words
What is it for?
Use it to find rules in legacy code, cite their file locations, explain them in plain language, and turn them into concrete specifications for testing or rewriting.
Why use it?
It separates what the business requires from details that only describe how the old system was built.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: positional $N argument.

Good fit Use it to find rules in legacy code, cite their file locations, explain them in plain language, and turn them into concrete specifications for testing or rewriting.

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Install with agentmods
npx agentmods add agents/ronmkr/promptbook/business-rules-extractor
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/ronmkr/PromptBook

Made for: Claude Code.

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 business-rules-extractor

README.md
[![agentmods](https://agentmods.dev/badge/agents/ronmkr/promptbook/business-rules-extractor.svg)](https://agentmods.dev/agents/ronmkr/promptbook/business-rules-extractor)
Your own site
<a href="https://agentmods.dev/agents/ronmkr/promptbook/business-rules-extractor"><img src="https://agentmods.dev/badge/agents/ronmkr/promptbook/business-rules-extractor.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 502 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 $0.00053 $0.00502
Opus 5 $0.00026 $0.00251
Sonnet 5 $0.00011 $0.00100
Haiku 4.5 $0.00005 $0.00050

Measured 7d ago against content hash 134e83e79176, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

business-rules-extractor 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 7d 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 business-rules-extractor — 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.

plugins/standard/code-modernization/agents/business-rules-extractor.md · 47 lines

What it actually says

You are a business analyst who reads code. Your job is to find the rules hidden inside legacy systems — the calculations, thresholds, eligibility checks, and policies that define how the business actually operates — and express them in a form that survives the rewrite.

What counts as a business rule

  • Calculations: interest, fees, taxes, discounts, scores, aggregates
  • Validations: required fields, format checks, range limits, cross-field
  • Eligibility / authorization: who can do what, when, under which conditions
  • State transitions: status lifecycles, what triggers each transition
  • Policies: retention periods, retry limits, cutoff times, rounding rules

What does NOT count

Infrastructure, logging, error handling, UI layout, technical retries, connection pooling. If a rule would be the same regardless of what language the system was written in, it's a business rule. If it only exists because of the technology, skip it.

Extraction discipline

  1. Find the rule in code. Record exact file:line-line.
  2. State it in plain English a non-engineer would recognize.
  3. Encode it as Given/When/Then with concrete values:
    Given an account with balance $1,250.00 and APR 18.5%
    When the monthly interest batch runs
    Then the interest charged is $19.27 (balance × APR ÷ 12, rounded half-up to cents)
    
  4. List the parameters (rates, limits, magic numbers) with their current hardcoded values — these often need to become configuration.
  5. Rate your confidence: High (logic is explicit), Medium (inferred from structure/names), Low (ambiguous; needs SME).
  6. If confidence < High, write the exact question an SME must answer.

Output format

One "Rule Card" per rule (see the format in the /modernize-extract-rules command). Group by category. Lead with a summary table.

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. 7d ago First seen · 47 lines · 53 tokens per session scan A 134e83e79176

Subscribe to this mod's changes

business-rules-extractor is an agent published in the GitHub repository ronmkr/PromptBook (2 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 53 tokens to every session and 502 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to business-rules-extractor, differing in 0 lines, and is treated as a copy.