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.
git clone --depth 1 https://github.com/matank001/cursor-security-rulesWrote 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.
[](https://agentmods.dev/rules/matank001/cursor-security-rules/secure-development-principles)<a href="https://agentmods.dev/rules/matank001/cursor-security-rules/secure-development-principles"><img src="https://agentmods.dev/badge/rules/matank001/cursor-security-rules/secure-development-principles/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/rules/matank001/cursor-security-rules/secure-development-principles"><img src="https://agentmods.dev/badge/rules/matank001/cursor-security-rules/secure-development-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00380 | $0.00380 |
| Opus 5.5 | $0.00152 | $0.00152 |
| Sonnet 5.5 | $0.00076 | $0.00076 |
| Haiku 4.5 | $0.00038 | $0.00038 |
Grade A, and why
secure-development-principles 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 1mo 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
Secure Development Principles
These rules define essential practices for writing and generating secure code.
They apply universally — to manual development, automated tooling, and AI-generated code.
All violations must include a clear explanation of which rule was triggered and why, to help developers understand and fix the issue effectively.
1. Do Not Use Raw User Input in Sensitive Operations
- Rule: Untrusted input must never be used directly in file access, command execution, database queries, or similar sensitive operations.
2. Do Not Expose Secrets in Public Code
- Rule: Secrets such as API keys, credentials, private keys, or tokens must not appear in frontend code, public repositories, or client-distributed files.
3. Enforce Secure Communication Protocols
- Rule: Only secure protocols (e.g., HTTPS, TLS) must be used for all external communications.
4. Avoid Executing Dynamic Code
- Rule: Dynamically constructed code or expressions must not be executed at runtime.
5. Validate All External Input
- Rule: Inputs from users, external APIs, or third-party systems must be validated before use.
6. Do Not Log Sensitive Information
- Rule: Logs must not contain credentials, tokens, personal identifiers, or other sensitive data.
7. Prevent Disabling of Security Controls
- Rule: Security checks must not be disabled, bypassed, or suppressed without documented and reviewed justification.
8. Limit Trust in Client-Side Logic
- Rule: Critical logic related to permissions, authentication, or validation must not rely solely on client-side code.
9. Detect and Eliminate Hardcoded Credentials
- Rule: Credentials must not be hardcoded in source files, configuration, or scripts.
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.
- 1mo ago First seen · 38 lines · 380 tokens per session scan A 8188b1892682
secure-development-principles is a cursor rule published in the GitHub repository matank001/cursor-security-rules (381 stars, last pushed 1y ago), licensed MIT. It adds 380 tokens to every session, about $0.0015 per session on Opus 5.5. 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.
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