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/ccashwell/evm-cortex/securitygit clone --depth 1 https://github.com/ccashwell/evm-cortexWhat 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 | $0.00433 | $0.00433 |
| Opus 5 | $0.00217 | $0.00217 |
| Sonnet 5 | $0.00087 | $0.00087 |
| Haiku 4.5 | $0.00043 | $0.00043 |
Grade A, and why
security 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
Smart Contract Security Rules
Mandatory Patterns
Checks-Effects-Interactions
Every state-changing function MUST follow this order:
- Validate inputs and permissions (checks)
- Update state variables (effects)
- Make external calls (interactions)
Reentrancy Protection
- Use OpenZeppelin ReentrancyGuard on any function making external calls
- Even with CEI pattern, add the guard as defense in depth
- Watch for read-only reentrancy through view functions
Token Safety
- ALWAYS use SafeERC20 for token transfers
- Check token decimals -- USDC=6, WBTC=8, most=18
- Handle fee-on-transfer tokens (received != sent)
- Handle rebasing tokens (stETH balance changes)
- Handle tokens with blocklists (USDC, USDT)
Access Control
- Every state-changing function needs explicit access control
- Use Ownable2Step (prevents accidental ownership transfer)
- Use AccessControl for multi-role systems
- Add timelock for admin functions affecting user funds
- Document all privileged roles
Input Validation
- Validate ALL external inputs (zero address, zero amount, bounds)
- Use custom errors with descriptive parameters
- Validate array lengths match in batch operations
Vulnerability Checklist (Before Every PR)
- No hardcoded secrets
- Checks-effects-interactions followed
- ReentrancyGuard on external call functions
- SafeERC20 used for all transfers
- Access control on all state-changing functions
- Events emitted for all state changes
- Edge cases handled (0, max, empty state)
- No tx.origin usage
- External call return values checked
- No delegatecall to untrusted addresses
When Security Issue Found
- STOP current work
- Classify severity (Critical/High/Medium/Low)
- Write PoC test demonstrating the issue
- Fix following the recommendation pattern
- Verify fix with the PoC test
- If secrets leaked: rotate immediately
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 · 54 lines · 433 tokens per session scan A 39e691a96820
security is a cursor rule published in the GitHub repository ccashwell/evm-cortex (127 stars, last pushed 22d ago), licensed MIT. It adds 433 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.
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