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 instructions/evmts/tevm/claude-mdgit clone --depth 1 https://github.com/evmts/tevmWhat 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 | $0.05351 | $0.05351 |
| Opus 5 | $0.02676 | $0.02676 |
| Sonnet 5 | $0.01070 | $0.01070 |
| Haiku 4.5 | $0.00535 | $0.00535 |
Grade A, and why
tevm CLAUDE.md 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.
How it starts
The opening of the file, as written. The whole thing — 478 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Tevm Monorepo Commands and Style Guide
Project Overview
Tevm is an in-browser & Node.js-compatible Ethereum Virtual Machine (EVM) environment. It provides a complete Ethereum execution environment powered by JavaScript that can run:
Unique Features:
-
Import Solidity contracts directly in JavaScript/TypeScript
-
Typecheck Solidity contracts with full type safety
-
Simulate and debug EVM execution step-by-step
-
Fork mainnet or any EVM chain locally in the browser
-
In Node.js for local development and testing
-
In the Browser for advanced user experiences (offline simulation, real-time testing)
-
In Deno, Bun, or any modern JavaScript runtime
Forking Implementation
Most of Tevm's forking logic is implemented in the StateManager. When a fork configuration is provided:
- The StateManager creates a proxy that intercepts data requests
- If data exists locally, it returns the local version
- If data doesn't exist locally, it fetches from the remote provider
- Fetched data is cached locally for future requests
- All state changes are applied only to the local state
This enables efficient forking with minimal memory usage, as only the accessed state is loaded and stored.
JSON-RPC Support
The entire JSON-RPC API is implemented in the tevm/actions package, which provides:
- Full support for standard Ethereum JSON-RPC methods (eth_*)
- Support for Anvil's methods (anvil_*)
- Debug namespace methods (debug_*)
- Custom Tevm methods (tevm_*)
These action handlers translate between Viem-style parameters and the internal Ethereumjs API, handling format conversions automatically.
Commands
- Build:
bun buildornx run-many --targets=build:dist,build:app,build:types - Lint:
bun lintorbiome check . --write --unsafe && biome format . --write - Test all:
bun testorbun test:run - Test single file:
vitest run <path-to-file>(e.g.vitest run packages/state/src/actions/saveStateRoot.spec.ts) - Test specific test:
vitest run <path-to-file> -t "<test-name>" - Test with coverage:
bun test:coverage
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 · 478 lines · 5,351 tokens per session scan A 85600904b668
tevm CLAUDE.md is an instructions file published in the GitHub repository evmts/tevm (446 stars, last pushed 2d ago), licensed MIT. It adds 5,351 tokens to every session, about $0.0268 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 2026-08-31.
Other instructions, from other repositories
prb-math AGENTS.md
Instructions for PaulRBerg/prb-math, covering prbmath, stack, structure, commands and development.
evmole AGENTS.md
Instructions for cdump/evmole: EVMole extracts structured facts from deployed EVM runtime bytecode.
solidity-language-server AGENTS.md
Instructions for asyncswap/solidity-language-server, covering agents, prerequisites: ast identity model, the two id types, the src string format and why file ids are unstable from solc.
solidity-typescript-hardhat-template CLAUDE.md
Instructions for protokol/solidity-typescript-hardhat-template, covering claude.md — project instructions, project overview, key commands, solidity conventions and test conventions.
foundry-template AGENTS.md
Instructions for PaulRBerg/foundry-template, covering agents.md, stack, commands, forge and bun scripts (package.json).
mcp-tenderly CLAUDE.md
Claude Code instructions for py-zoid/mcp-tenderly, covering mcp-tenderly, commands, layout, constraints worth knowing before you change anything and testing against real tenderly.