Web3 Core Operations

ERC20 Allowance Manager - Skill Specification

Skill ID

erc20-allowance-manager

Category

Web3 Core Operations

Overview

Comprehensive ERC20 token allowance management system with real blockchain queries via RPC, supporting multiple approval strategies, security risk assessment, and batch operations.

Capabilities

Core Functions

1. check - Query current allowance for token/spender pair
2. approve - Set token allowance with multiple strategies
3. revoke - Revoke token allowance (set to 0)
4. batch_check - Check allowances for multiple spenders simultaneously

Approval Strategies

• unlimited - Approve maximum uint256 (infinite)
• exact - Approve specific amount
• increase - Increase existing allowance
• safe - Safe approval pattern (revoke then approve)

Input Format

Parameters

{
  "owner": "0x...",           // Token owner wallet address (required)
  "token": "0x...",           // ERC20 token contract address (required)
  "action": "check|approve|revoke|batch_check",  // Operation (default: check)
  "spender": "0x...",         // Spender contract address (required for check/approve/revoke)
  "amount": "1000.00",        // Amount to approve (optional, for exact/increase)
  "strategy": "exact",        // Approval strategy (default: exact)
  "spenders": ["0x...", "0x..."]  // Array of spenders (required for batch_check)
}

Output Format

Success Response (check action)

{
  "success": true,
  "action": "check",
  "owner": "0x...",
  "token": {
    "address": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "symbol": "USDC",
    "decimals": 6,
    "name": "USD Coin"
  },
  "spender": {
    "address": "0x68b3465833fb72B5A828cCEEB955439B22B36987",
    "name": "Uniswap V3 Router",
    "category": "dex",
    "risk_level": "low"
  },
  "allowance": {
    "amount": "1000000000",     // Raw wei/units
    "amount_decimal": 1000000.0, // Decimal-adjusted
    "is_unlimited": false,
    "expires_at": null
  },
  "risk_assessment": {
    "is_unlimited": false,
    "is_suspicious_spender": false,
    "balance_ratio": 0.5,
    "risk_level": "low",
    "recommendations": []
  },
  "block_number": 24398547,
  "rpc_used": "https://eth-mainnet.public.blastapi.io",
  "timestamp": "2026-02-06T20:36:00Z"
}

Success Response (approve action)

{
  "success": true,
  "action": "approve",
  "owner": "0x...",
  "token": {...},
  "spender": {...},
  "approval": {
    "amount": "1000000000",
    "amount_decimal": 1000.0,
    "strategy": "exact",
    "transaction": {
      "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
      "data": "0x095ea7b3...",
      "gas_limit": 60000,
      "gas_price_gwei": 35.0,
      "estimated_cost_usd": 2.50
    }
  },
  "block_number": 24398547,
  "timestamp": "2026-02-06T20:36:00Z"
}

Success Response (batch_check action)

{
  "success": true,
  "action": "batch_check",
  "owner": "0x...",
  "token": {...},
  "results": [
    {
      "spender": {...},
      "allowance": {...},
      "risk_assessment": {...}
    }
  ],
  "summary": {
    "total_checked": 3,
    "unlimited_approvals": 1,
    "suspicious_spenders": 0
  },
  "timestamp": "2026-02-06T20:36:00Z"
}

Error Response

{
  "success": false,
  "error": "validation_error|connection_error|dependency_error|system_error",
  "message": "Human-readable error description"
}

Error Handling

Configuration

Environment Variables

ETHEREUM_RPC=https://eth-mainnet.public.blastapi.io  # Custom RPC endpoint (optional)

Known Spenders Registry

• Uniswap V3 Router: 0xE592427A0AEce92De3Edee1F18E0157C05861564
• Uniswap V2 Router: 0x7a250d5630b4cf539739df2c5dacb4c659f2488d
• 1inch Router: 0x1111111254fb6c44bac0bed2854e76f90643097d
• OpenSea Permit2: 0x000000000022D473030F116dFC393057B8271AC6
• Permit2: 0x000000000022D473030F116dFC393057B8271AC6

Token Registry

• USDC: 0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48 (6 decimals)
• USDT: 0xdac17f958d2ee523a2206206994597c13d831ec7 (6 decimals)
• WETH: 0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2 (18 decimals)
• DAI: 0x6b175474e89094c44da98b954eedeac495271d0f (18 decimals)
• WBTC: 0x2260fac5e5542a773aa44fbcff9d822a3ecee8e7 (8 decimals)

Dependencies

Required

• web3 >= 6.0 (Install via: pip install web3)
• Python 3.8+

Optional

• None

Blockchain Integration

RPC Method

• Provider: Ethereum mainnet via RPC endpoint
• Methods Used:
  • eth_blockNumber - Get current block
  • eth_call - Query allowance(owner, spender)
  • eth_getBalance - Get token balance

Smart Contracts

• ERC20 Interface: Standard allowance() function
• Permit2: Optional approval delegation

Validation Rules

1. Address Validation: Must be 42-character hex string starting with 0x
2. Amount Validation: Must be positive number or "unlimited"
3. Strategy Validation: Must be one of: unlimited, exact, increase, safe
4. Action Validation: Must be one of: check, approve, revoke, batch_check
5. Batch Size: Maximum 50 spenders per batch_check

Security Considerations

1. Risk Levels:

   • Low: Known protocol, reasonable amount, temporary approval
   • Medium: Unknown spender, high amount
   • High: Unlimited approval, suspicious spender, emergency alert

2. Risk Flags:

   • Unlimited approvals with no expiration
   • Unknown/suspicious spender contracts
   • Approval amount exceeds available balance
   • Repeated approvals to same spender

3. Best Practices:

   • Use exact amount instead of unlimited when possible
   • Revoke unused approvals regularly
   • Check spender before approving
   • Use safe strategy for critical tokens

Performance

• Response Time: < 2 seconds per check
• Batch Operations: < 5 seconds for 50 spenders
• Gas Estimation: Included in approval/revoke operations
• Rate Limits: No application-level limits

Supported Networks

Currently supports Ethereum mainnet. Future versions may add:

• Polygon
• Arbitrum
• Optimism
• Base
• Other EVM chains

Testing

Test Cases Included

• ✅ USDC allowance check (mainnet data)
• ✅ Approval with exact amount strategy
• ✅ Revoke allowance operation
• ✅ Batch check multiple spenders
• ✅ Risk assessment for unlimited approvals
• ✅ Known spender identification
• ✅ Error handling for invalid addresses

Example Test

echo '{
  "owner": "0x1234567890123456789012345678901234567890",
  "spender": "0x68b3465833fb72B5A828cCEEB955439B22B36987",
  "token": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
  "action": "check"
}' | python3 scripts/main.py

Version History

• v1.0.0 (Feb 2026)
  • Initial release with web3.py RPC integration
  • Support for check, approve, revoke, batch_check actions
  • Real blockchain queries instead of simulator
  • Known spender identification
  • Risk assessment framework

Author

web3devzz

License

MIT

Related Skills

• wallet-multisend - Multi-recipient token transfers
• token-liquidity-scan - Liquidity pool analysis
• erc20-transfer-monitor - Token transfer tracking