Tool Execution

When the chat agent decides to call a HYRE endpoint, it triggers a relay pattern that deducts the fee from the user’s escrow balance and forwards the request to the API.

Execution Flow

Chat Agent (Gemini)
  |
  | tool_call: { name: "token-verdict", params: { mint: "7xKX..." } }
  |
  v
/playground/call (backend)
  |
  |-- 1. Validate Privy JWT
  |-- 2. Check escrow balance >= endpoint price
  |-- 3. Deduct price from escrow
  |-- 4. Forward request to HYRE API with X-Internal-Auth header
  |-- 5. Return response to chat agent
  |
  v
Chat Agent formats + streams response to user

Payment Signing (EVM Chains)

On Base and SKALE, the backend uses EIP-3009 TransferWithAuthorization to sign USDC transfers from the custodial wallet:

The backend decrypts the user’s wallet private key.
It constructs a TransferWithAuthorization payload with:
- from: user’s custodial wallet
- to: HYRE recipient address
- value: endpoint price in atomic USDC
- validAfter: current timestamp
- validBefore: current timestamp + 300 seconds
Signs the EIP-712 typed data with the decrypted key.
The fee payer submits the signed authorization on-chain.
A real transaction hash is returned and verifiable on the block explorer.

On Solana, the escrow uses an internal balance ledger with periodic on-chain settlement rather than per-query transactions. This reduces gas overhead.

Internal Auth Bypass

The /playground/call endpoint bypasses the x402 payment middleware using a shared secret (MPP_SECRET_KEY):

X-Internal-Auth: <MPP_SECRET_KEY>

This header is only known to the Cloudflare Worker itself. External clients cannot forge it. The x402 middleware checks for this header before requiring payment, allowing the playground to pre-authorize queries via the escrow balance.

Error Handling

Scenario	Behavior
Insufficient balance	Error returned before API call. No charge.
API call fails (5xx)	Balance refunded. Error shown in chat.
LLM cascade fails	HTTP 206 returned with raw data. User still charged (data was delivered).
Invalid parameters	Validation error returned. No charge.
Network timeout	Automatic retry once. If second attempt fails, balance refunded.

Transaction Verification

Every paid query returns metadata that can be verified:

{
  "payment": {
    "amount_usdc": 0.015,
    "chain": "solana",
    "tx_hash": "4vJ9JU1bJJE96FWSJKvHsmmFAD...",
    "explorer": "https://solscan.io/tx/4vJ9JU1bJJE96FWSJKvHsmmFAD...",
    "deducted_from_escrow": true
  }
}

On SKALE, transaction hashes can be verified on the SKALE Europa explorer.

Getting Started

LLM Gateway

Agent Playground

Payment

Architecture

ME Protocol

API Reference

Tool Execution

Tool Execution

Execution Flow

Payment Signing (EVM Chains)

Internal Auth Bypass

Error Handling

Transaction Verification

​Tool Execution

​Execution Flow

​Payment Signing (EVM Chains)

​Internal Auth Bypass

​Error Handling

​Transaction Verification

Tool Execution

Execution Flow

Payment Signing (EVM Chains)

Internal Auth Bypass

Error Handling

Transaction Verification