Skillhub

AI-powered agent skill generator for smart contracts.

Skillhub is an HTTP API that generates Agent Skills (SKILL.md files) from Ethereum smart contract addresses. Skills are gated behind x402 micropayments (USDC on Base Mainnet) and stored permanently on IPFS.

Why

AI agents interacting with smart contracts either waste context tokens parsing raw ABIs, hallucinate function signatures, or ask the human — defeating the purpose of autonomy. Skillhub provides a cheaper, faster, higher-quality alternative: pay $0.10, get a concise, validated, context-efficient skill file ready to use in any agent.

API

Method	Path	Price	Description
POST	/skills/generate	$0.10 USDC	Kick off async skill generation
GET	/skills/status/:sid	free	Poll session state
GET	/skills/:id	$0.01 USDC	Fetch completed skill by IPFS CID
GET	/health	free	Health check

Generate a skill

POST /skills/generate
Content-Type: application/json

{ "contractAddress": "0x...", "chainId": 8453 }

Response:

{ "sessionId": "...", "statusUrl": "/skills/status/..." }

Poll for completion

GET /skills/status/:sid

Response when ready:

{ "status": "ready", "skillId": "<ipfs-cid>" }

Fetch the skill

GET /skills/<ipfs-cid>

Returns the raw SKILL.md content. Endpoint is x402-gated ($0.01 USDC).

All paywalled endpoints are auto-indexed in x402 Bazaar for discovery by other agents.

Tech Stack

• Runtime: Node.js (ES modules)
• Framework: Express
• AI: LangChain + LangGraph (ReAct agent), OpenAI LLM
• Payments: @x402/express + @x402/evm — USDC on Base Mainnet via PayAI facilitator
• Discovery: x402 Bazaar (auto-indexed on payment settlement)
• Storage: IPFS via Pinata SDK (content-addressed, pinned; retrieved via dedicated gateway)
• Block explorer: Uniblock API (ABI, verified source, proxy resolution)
• EVM client: viem (used in generated code examples)
• Wallet: Open Wallet Standard (ows CLI) via the bundled ows-sign skill

Setup

cp .env.example .env
# fill in required values
npm install
npm start

Environment variables

Variable	Required	Description
OPENAI_API_KEY	yes	OpenAI API key
UNIBLOCK_API_KEY	yes	Uniblock API key for ABI + source fetching
PINATA_JWT	yes	Pinata JWT for IPFS pinning
EVM_ADDRESS	yes	Wallet address to receive x402 payments (Base Mainnet)
PORT	no	HTTP port (default: 3000)
OPENAI_MODEL	no	LLM model (default: gpt-4o)
PINATA_GATEWAY	no	Pinata dedicated gateway domain
PAYAI_API_KEY_ID	no	PayAI API key (free tier works without)
PAYAI_API_KEY_SECRET	no	PayAI API secret

Pipeline

Skill generation runs three async stages with up to 3 total attempts (retry with failure feedback):

1. Research — LangGraph ReAct agent calls Uniblock to fetch the contract ABI, verified source code, and detected ERC patterns. Automatically resolves EIP-1967 proxy contracts to their implementation.
2. Generate — LLM model produces a SKILL.md from the research context, targeting <500 lines / <5000 tokens.
3. Validate — Three checks: required frontmatter fields, ABI cross-check (code examples match function signatures), safety check (warnings present for payable functions and approval patterns).

On validation failure the reason is passed back to the next generate attempt for self-correction.

Skillhub skill

skills/skillhub/SKILL.md is Skillhub's own agent skill — it tells any compatible agent how to use the Skillhub API: generate a skill for a contract, poll for completion, and download the result via x402 payments using OWS CLI. It is served at GET /skill.md.

ows-sign skill

Skillhub ships a bundled agent skill at skills/ows-sign/SKILL.md that enables any Claude Code (or compatible) agent to sign and broadcast EVM transactions using the Open Wallet Standard CLI — without exposing private keys.

What it does

• Encodes calldata for any contract function via a local scripts/encode-tx.mjs helper
• Signs and broadcasts the encoded transaction through ows sign + ows broadcast
• Works on any EVM chain; tested on Base Mainnet (chainId 8453)

Prerequisites

• ows CLI installed and a wallet configured (ows wallet list)
• node available for the encode-tx script

Usage

Install the skill into your agent session:

/skill skills/ows-sign/SKILL.md

The agent will use the ows-sign workflow whenever it needs to call a contract function on-chain.

Output format

Generated skills follow the open Agent Skills specification — no vendor lock-in. Code examples use viem.