Borrowing it
Nothing to install: this file belongs to Hirama/solidity-agentic-stack. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Hirama/solidity-agentic-stack/main/.claude/skills/foundry-cast/SKILL.mdgit clone --depth 1 https://github.com/Hirama/solidity-agentic-stackWrote 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/hirama/solidity-agentic-stack/foundry-cast)<a href="https://agentmods.dev/skills/hirama/solidity-agentic-stack/foundry-cast"><img src="https://agentmods.dev/badge/skills/hirama/solidity-agentic-stack/foundry-cast/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/hirama/solidity-agentic-stack/foundry-cast"><img src="https://agentmods.dev/badge/skills/hirama/solidity-agentic-stack/foundry-cast.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 | $0.00075 | $0.01759 |
| Opus 5.5 | $0.00030 | $0.00704 |
| Sonnet 5.5 | $0.00015 | $0.00352 |
| Haiku 4.5 | $0.00007 | $0.00176 |
Grade A, and why
foundry-cast scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 196 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cast — Foundry's Chain CLI
cast is the read-side counterpart to forge. Every chain operation an agent might want from an MCP server is already a cast subcommand. No server, no daemon, no shebang bugs — just the binary that ships with Foundry.
Full reference: https://getfoundry.sh/cast
When to use this skill
- Inspecting a deployed contract (bytecode, storage, ABI)
- Decoding a transaction's calldata or revert reason
- Looking up a 4-byte selector or event signature
- Fetching balance, nonce, code at an address
- Reading state via
eth_callwithout writing a Forge test - Resolving ENS names
- Encoding calldata for a script
Setup
cast needs an RPC. Either pass --rpc-url per command or set ETH_RPC_URL:
export ETH_RPC_URL=https://eth.blockscout.com/api/eth-rpc # free, no key
# or
export ETH_RPC_URL=$RPC_MAINNET # from .env
Blockscout's public RPC is the simplest no-key fallback for read-only ops.
Read-only cheat sheet
Account state
cast balance vitalik.eth # ETH balance (wei)
cast balance vitalik.eth --ether # in ETH
cast nonce 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 # tx count
cast code 0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48 # runtime bytecode
cast codesize 0xa0b8...eb48
cast storage 0xa0b8...eb48 0 # slot 0
cast proof 0xa0b8...eb48 0 # merkle proof for slot
Block / chain
cast block-number
cast block latest
cast gas-price
cast chain-id
cast base-fee
cast age <block> # human time
cast find-block <timestamp> # block at unix time
Transactions
cast tx <hash> # tx envelope
cast receipt <hash> # receipt + logs
cast run <hash> # re-execute & trace
cast trace <hash> # full call trace
cast decode-transaction <raw-hex>
cast 4byte-calldata 0xa9059cbb... # match selector → sig
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.
- 2mo ago First seen · 196 lines · 75 tokens per session scan A 1acd90940bf5
foundry-cast is a skill published in the GitHub repository Hirama/solidity-agentic-stack (6 stars, last pushed 4mo ago), licensed MIT. It adds 75 tokens to every session and 1,759 once invoked, about $0.0003 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 2026-08-31.
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