architecture

A set of required design and coding rules for the mcp-prometheus Go project. It covers tests, formatting, error handling, file size, dependencies, and documentation.

In plain words
What is it for?
Use it when adding or changing Go code to check test coverage, avoid flaky tests, format files, preserve error context, limit file size, and document packages and exported code.
Why use it?
It keeps the code easier to test, understand, and maintain by making project-wide expectations explicit.

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/giantswarm/mcp-prometheus/architecture
Clone the repo
git clone --depth 1 https://github.com/giantswarm/mcp-prometheus

Made for: Cursor.

Per session 332 This file is loaded in full into every session.
When invoked 332 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin 92% 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 $0.00332 $0.00332
Opus 5 $0.00166 $0.00166
Sonnet 5 $0.00066 $0.00066
Haiku 4.5 $0.00033 $0.00033

Measured yesterday against content hash f4e424ecba90, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

architecture 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.

Origin

This is a copy

92% identical to architecture — 4 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.

.cursor/rules/architecture.mdc · 37 lines

What it actually says

Architecture Principles

This document outlines the fundamental architectural principles and patterns for the mcp-prometheus codebase. Adherence to these guidelines is mandatory to maintain a clean, decoupled, and testable system.


1. Testing Standards

  • Minimum Coverage: All new code MUST achieve at least 80% unit test coverage.
  • No Flaky Tests: Tests MUST be deterministic. Do not use time.Sleep or other mechanisms that can lead to race conditions. Use dependency injection for things like clocks or timers to make code testable.

2. Go Development & Style

  • Formatting: Before every commit, run:
    goimports -w .
    go fmt ./...
    
  • Dependencies: Before adding a new dependency with go get, search the web to find its latest stable version. This is a must!
  • Error Handling: Wrap errors with fmt.Errorf("context: %w", err) to preserve context.
  • File Size: Keep files focused and under 500 lines. Refactor larger files.

3. Documentation

  • Packages: Every package MUST have a doc.go file explaining its purpose.
  • Exported Members: Every exported function, type, and variable MUST have a GoDoc comment.
  • Project Docs: New features or significant changes require updates to the relevant documents in the docs/ directory.
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 · 37 lines · 332 tokens per session scan A f4e424ecba90

Subscribe to this mod's changes

architecture is a cursor rule published in the GitHub repository giantswarm/mcp-prometheus (10 stars, last pushed 2d ago), licensed Apache-2.0. It adds 332 tokens to every session, about $0.0017 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to architecture, differing in 4 lines, and is treated as a copy.