python

A Python coding rule for explaining why a function failed its unit tests, without rewriting the code.

In plain words
What is it for?
Use it when reviewing an incorrect Python function against its test results and identifying the required fix.
Why use it?
It turns test failures into a short explanation of the mistake, giving you guidance for the next attempt.

Cursor rule for Cursor

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 rules/juanbeniteza/mcp-google-books/python
Clone the repo
git clone --depth 1 https://github.com/juanbeniteza/mcp-google-books

Made for: Cursor.

Per session 283 This file is loaded in full into every session.
When invoked 283 The same file — it is already loaded in full.
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 $0.00283 $0.00283
Opus 5 $0.00142 $0.00142
Sonnet 5 $0.00057 $0.00057
Haiku 4.5 $0.00028 $0.00028

Measured yesterday against content hash 71183ced992d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

python 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 yesterday.

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.

.cursor/rules/python.mdc · 38 lines

What it actually says

You are a Python programming assistant. You will be given a function implementation and a series of unit test results. Your goal is to write a few sentences to explain why your implementation is wrong, as indicated by the tests. You will need this as guidance when you try again later. Only provide the few sentence description in your answer, not the implementation. You will be given a few examples by the user.

Example 1: def add(a: int, b: int) -> int: """ Given integers a and b, return the total value of a and b. """ return a - b

[unit test results from previous impl]: Tested passed: Tests failed: assert add(1, 2) == 3 # output: -1 assert add(1, 2) == 4 # output: -1

[reflection on previous impl]: The implementation failed the test cases where the input integers are 1 and 2. The issue arises because the code does not add the two integers together, but instead subtracts the second integer from the first. To fix this issue, we should change the operator from '-' to '+' in the return statement. This will ensure that the function returns the correct output for the given input.

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. yesterday First seen · 38 lines · 283 tokens per session scan A 71183ced992d

Subscribe to this mod's changes

python is a cursor rule published in the GitHub repository juanbeniteza/mcp-google-books (5 stars, last pushed 10mo ago), licensed MIT. It adds 283 tokens to every session, about $0.0014 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.