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 skills add ccashwell/evm-cortex --skill anvil-patternsgit clone --depth 1 https://github.com/ccashwell/evm-cortexWrote 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/skills/ccashwell/evm-cortex/anvil-patterns)<a href="https://agentmods.dev/skills/ccashwell/evm-cortex/anvil-patterns"><img src="https://agentmods.dev/badge/skills/ccashwell/evm-cortex/anvil-patterns/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/skills/ccashwell/evm-cortex/anvil-patterns"><img src="https://agentmods.dev/badge/skills/ccashwell/evm-cortex/anvil-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 158 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00039 | $0.01590 |
| Opus 5.5 | $0.00016 | $0.00636 |
| Sonnet 5.5 | $0.00008 | $0.00318 |
| Haiku 4.5 | $0.00004 | $0.00159 |
Grade A, and why
anvil-patterns 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.
How it starts
The opening of the file, as written. The whole thing — 205 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Anvil Local Node Patterns
Basic Usage
# Start default local node (8545)
anvil
# Custom port and chain ID
anvil --port 8546 --chain-id 31337
# With specific number of accounts and balance
anvil --accounts 20 --balance 10000
# Specific mnemonic (reproducible addresses)
anvil --mnemonic "test test test test test test test test test test test junk"
# Specific block base fee
anvil --block-base-fee-per-gas 0
Forking
Fork mainnet or any chain at the current or a specific block:
# Fork mainnet (latest block)
anvil --fork-url $ETH_RPC_URL
# Fork at specific block (reproducible state)
anvil --fork-url $ETH_RPC_URL --fork-block-number 18000000
# Fork Base
anvil --fork-url $BASE_RPC_URL --chain-id 8453
# Fork with retry and rate limiting
anvil --fork-url $ETH_RPC_URL --fork-retry-backoff 3 --compute-units-per-second 100
# No storage caching (fresh state each time)
anvil --fork-url $ETH_RPC_URL --no-storage-caching
Impersonation
Send transactions as any address without its private key:
# Impersonate an address via RPC
cast rpc anvil_impersonateAccount 0xWhaleAddress
# Send tx as the impersonated address
cast send 0xToken "transfer(address,uint256)" 0xRecipient 1000000000000000000 \
--from 0xWhaleAddress --unlocked --rpc-url http://127.0.0.1:8545
# Stop impersonating
cast rpc anvil_stopImpersonatingAccount 0xWhaleAddress
In Foundry tests, use vm.prank() instead:
vm.prank(0xWhaleAddress);
token.transfer(recipient, amount);
Mining Modes
# Auto-mine (default): mine a block for each transaction
anvil
# Interval mining: mine every N seconds
anvil --block-time 12
# Manual mining: no auto-mining
anvil --no-mining
# Mine a single block manually
cast rpc evm_mine --rpc-url http://127.0.0.1:8545
# Mine N blocks
cast rpc anvil_mine 10 --rpc-url http://127.0.0.1:8545
# Mine with specific timestamp
cast rpc evm_mine "0x$(printf '%x' 1700000000)" --rpc-url http://127.0.0.1:8545
State Manipulation
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 · 205 lines · 39 tokens per session scan A 679a42b0e737
anvil-patterns is a skill published in the GitHub repository ccashwell/evm-cortex (131 stars, last pushed 17d ago), licensed MIT. It adds 39 tokens to every session and 1,590 once invoked, about $0.0002 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 2026-09-03.
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