API Reference

JSON-RPC API

Monmouth exposes a standard Ethereum JSON-RPC API with additional agent-specific methods.

Endpoint

https://rpc.monmouth.io

Testnet:

https://testnet-rpc.monmouth.io

Standard Methods

All standard Ethereum JSON-RPC methods are supported:

• eth_blockNumber
• eth_getBalance
• eth_getTransactionByHash
• eth_sendRawTransaction
• eth_call
• eth_estimateGas
• ... and more

Agent Methods

Additional methods for agent operations:

monmouth_getAgentIdentity

Get agent identity details.

{
  "jsonrpc": "2.0",
  "method": "monmouth_getAgentIdentity",
  "params": ["did:monmouth:agent:0x..."],
  "id": 1
}

Response:

{
  "result": {
    "did": "did:monmouth:agent:0x...",
    "owner": "0x...",
    "guardians": ["0x..."],
    "reputation": {
      "score": 98.5,
      "transactions": 1542
    },
    "createdAt": "2025-01-01T00:00:00Z"
  }
}

monmouth_resolveIntent

Resolve an intent without executing.

{
  "jsonrpc": "2.0",
  "method": "monmouth_resolveIntent",
  "params": [{
    "type": "swap",
    "fromToken": "ETH",
    "toToken": "USDC",
    "amount": "1000000000000000000"
  }],
  "id": 1
}

Response:

{
  "result": {
    "confidence": 0.95,
    "route": ["WETH", "USDC"],
    "protocol": "uniswap-v3",
    "estimatedOutput": "1842500000",
    "estimatedGas": 180000,
    "transaction": {
      "to": "0x...",
      "data": "0x...",
      "value": "1000000000000000000"
    }
  }
}

monmouth_executeIntent

Execute an intent.

{
  "jsonrpc": "2.0",
  "method": "monmouth_executeIntent",
  "params": [{
    "type": "swap",
    "fromToken": "ETH",
    "toToken": "USDC",
    "amount": "1000000000000000000"
  }, "0x...signature"],
  "id": 1
}

monmouth_getGuardrailUsage

Get current guardrail usage for an agent.

{
  "jsonrpc": "2.0",
  "method": "monmouth_getGuardrailUsage",
  "params": ["did:monmouth:agent:0x..."],
  "id": 1
}

Response:

{
  "result": {
    "dailySpent": "3500000000000000000",
    "dailyLimit": "10000000000000000000",
    "weeklySpent": "12000000000000000000",
    "weeklyLimit": "50000000000000000000"
  }
}

WebSocket API

Real-time subscriptions via WebSocket:

wss://ws.monmouth.io

Subscriptions

newAgentTransactions

Subscribe to transactions for an agent:

{
  "jsonrpc": "2.0",
  "method": "eth_subscribe",
  "params": ["newAgentTransactions", "did:monmouth:agent:0x..."],
  "id": 1
}

guardrailAlerts

Subscribe to guardrail threshold alerts:

{
  "jsonrpc": "2.0",
  "method": "eth_subscribe",
  "params": ["guardrailAlerts", {
    "agent": "did:monmouth:agent:0x...",
    "threshold": 0.8
  }],
  "id": 1
}

SDK Reference

See the Wallet SDK documentation for the TypeScript SDK reference.

Rate Limits

Tier	Requests/second	WebSocket connections
Free	10	2
Developer	100	10
Enterprise	Unlimited	Unlimited

Error Codes

Code	Description
-32000	Generic server error
-32001	Agent not found
-32002	Guardrail violation
-32003	Policy violation
-32004	Insufficient funds
-32005	Intent resolution failed
-32006	Cross-chain error