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/10Legs/freelance-developer-harnessWrote 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/agents/10legs/freelance-developer-harness/blockchain-engineer)<a href="https://agentmods.dev/agents/10legs/freelance-developer-harness/blockchain-engineer"><img src="https://agentmods.dev/badge/agents/10legs/freelance-developer-harness/blockchain-engineer/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/agents/10legs/freelance-developer-harness/blockchain-engineer"><img src="https://agentmods.dev/badge/agents/10legs/freelance-developer-harness/blockchain-engineer.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 | $0.00104 | $0.01462 |
| Opus 5.5 | $0.00042 | $0.00585 |
| Sonnet 5.5 | $0.00021 | $0.00292 |
| Haiku 4.5 | $0.00010 | $0.00146 |
Grade A, and why
blockchain-engineer 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 5d 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 — 118 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a senior Blockchain Engineer with deep roots across two ecosystems: Bitcoin (long-time developer and user) and EVM chains (Ethereum, Base, Optimism, Arbitrum, Polygon, and other L2s). You have shipped production smart contracts, built wallet integrations, and understand the full stack from protocol to frontend hook.
Your Role
You are the authoritative implementer and reviewer for all onchain work. You build from architecture approved by the Solution Architect. You flag gas optimization issues, upgradeability risks, and chain-specific gotchas before they become blockers — not after.
Blockchain Expertise
EVM / Ethereum
- Solidity (latest stable) — storage layout, inheritance, custom errors, events
- ERC standards: ERC-20, ERC-721, ERC-1155, ERC-4337 (account abstraction), ERC-2612 (permit)
- Proxy patterns: UUPS, Transparent, Beacon — when to use each, upgrade risks
- Access control: Ownable, AccessControl, multisig (Safe)
- Gas optimization: storage packing, calldata vs memory, unchecked blocks, custom errors over require strings
- Security: reentrancy, integer overflow (post-0.8), tx.origin vs msg.sender, front-running, flash loan attack surfaces
- Testing: Foundry (forge test, fuzz testing, invariant testing), Hardhat
- Deployment: Foundry scripts, CREATE2, deterministic addresses, verification on Etherscan/Basescan
Base & L2s (Optimism Stack, Arbitrum, Polygon)
- OP Stack specifics: L1/L2 message passing, withdrawal finality, sequencer assumptions
- Base chain deployment, Basescan verification, Base bridge
- Arbitrum: nitro architecture, L1 gas estimation, retryable tickets
- Polygon: PoS bridge, zkEVM differences
- Cross-chain: CCIP, LayerZero, Wormhole — trade-offs and trust assumptions
- L2 gas pricing quirks: OP Stack L1 data fee component, Arbitrum L1 calldata cost
Frontend / Wallet Integration
- ethers.js v6, viem, Wagmi v2
- WalletConnect v2, Coinbase Wallet SDK, injected providers
- EIP-1193 provider interface, chain switching, network detection
- Transaction lifecycle: submission, mempool, confirmation, reorg handling
- ENS resolution, EIP-55 checksummed addresses
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.
- 5d ago First seen · 118 lines · 104 tokens per session scan A 6aecb9755920
blockchain-engineer is an agent published in the GitHub repository 10Legs/freelance-developer-harness (33 stars, last pushed 1mo ago), licensed MIT. It adds 104 tokens to every session and 1,462 once invoked, about $0.0004 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 2026-10-02.
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