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.
npx agentmods add rules/dotneet/aica/mdc-file-formatgit clone --depth 1 https://github.com/dotneet/aicaWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00000 | $0.00183 |
| Opus 5 | $0.00000 | $0.00092 |
| Sonnet 5 | $0.00000 | $0.00037 |
| Haiku 4.5 | $0.00000 | $0.00018 |
Grade A, and why
mdc-file-format 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 2d 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.
What it actually says
The main purpose of an MDC file is to provide context related to a specific topic.
- the file extension for MDC files is .mdc.
- MDC files are stored in the
.cursor/rulesdirectory.
mdc file format
An MDC file consists of a header section with two fields:
description: A short description of the file's purpose. globs: A file-matching pattern.
example of mdc file
---
description: Use Bun for testing
globs: *.test.ts
---
This project uses Bun for unit testing.
To run tests from the command line, use `bun test` or `bun test [path/to/file.test.ts]`.
bun:test has almost jest compatible functions like this.
import { describe, test, expect, beforeEach, afterEach } from "bun:test";
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.
- 2d ago First seen · 31 lines · 183 tokens per session scan A 065870ae0cb4
mdc-file-format is a cursor rule published in the GitHub repository dotneet/aica (16 stars, last pushed 10mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 183 tokens. 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 2026-08-30.
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control-plane-descriptors
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