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/fredantb/spec-driven-development/cursorrulesgit clone --depth 1 https://github.com/FredAntB/Spec-Driven-DevelopmentWhat 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 | $0.00430 | $0.00430 |
| Opus 5 | $0.00215 | $0.00215 |
| Sonnet 5 | $0.00086 | $0.00086 |
| Haiku 4.5 | $0.00043 | $0.00043 |
Grade A, and why
cursorrules 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.
What it actually says
.cursorrules
Project: Freelance Time Tracker — v1.0
═══════════════════════════════════════════════════════════ SPEC DRIVEN DEVELOPMENT — PROJECT CONSTITUTION Project: Freelance Time Tracker Version: v1.0
This project uses Spec Driven Development. All work is governed by three source-of-truth files:
requirements.md — What the system must do design.md — How the system is structured tasks.md — The ordered implementation plan
MANDATORY BEFORE ANY ACTION: 0. If CONTEXT.md exists, read it first — it has session state
- Read requirements.md in full
- Read design.md in full
- Read tasks.md — find the next incomplete [ ] task
HARD CONSTRAINTS:
- Implement ONLY what is in requirements.md
- Match EXACTLY the data model in design.md
- Create ONLY files listed or implied by design.md
- Never mark a task [x] without verifying its acceptance criterion
- If a requirement is ambiguous: ASK, do not guess
- If scope creep is detected: FLAG it, do not implement
AFTER COMPLETING A TASK:
- Run the verification step listed in tasks.md
- Mark the task [x] in tasks.md
- Report what was done and which REQ/NFR it satisfies
DIVERGENCE PROTOCOL: If implementation must deviate from design.md: 1. Stop immediately 2. Describe the conflict to the user 3. Wait for explicit approval to update design.md 4. Update design.md FIRST, then implement ═══════════════════════════════════════════════════════════
Cursor-Specific
- Apply these rules to all file types in the project.
- In Composer mode, re-read the three spec files at the start of each new Composer session.
- Do not accept @codebase suggestions that conflict with design.md — flag the conflict instead.
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.
- yesterday First seen · 47 lines · 430 tokens per session scan A 410e187f7ec8
cursorrules is a cursor rule published in the GitHub repository FredAntB/Spec-Driven-Development (152 stars, last pushed 3mo ago), licensed MIT. It adds 430 tokens to every session, about $0.0022 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 2026-08-30.
Other cursor rules, from other repositories
pytest-integration-tests
Below is an example test. Notice the following.
python-app
Cursor rule "python-app" from iloveitaly/llm-ide-rules, covering python app, factories and database & orm.
react
Cursor rule "react" from iloveitaly/llm-ide-rules, covering react, mock data, react hook form and styling.
alembic-migrations
To add a non-nullable column and set a specific value for all existing rows without a persistent server default.
read-xlsx
Reading, writing, diffing, and repairing spreadsheets (.xlsx) for AI agents via the xfa MCP server.
justfiles
Justfiles.