x402 Payment Protocol for TRON Agents

Invoke x402-enabled AI agent endpoints with automatic TRC20 token payments on TRON.

Currently recommended tokens: USDT, USDD.

Quick Start

The tool x402_tron_invoke is implemented by the compiled script dist/x402_tron_invoke.js.

The script is pre-built and ready to run. You can execute it directly from the command line:

# v2 Invoke
node dist/x402_tron_invoke.js --url https://api.example.com --entrypoint chat --input '{"prompt": "hi"}'

# Direct/Discovery
node dist/x402_tron_invoke.js --url https://api.example.com/.well-known/agent.json

How It Works

The x402_tron_invoke tool:

1. Constructs the endpoint URL:
• If entrypoint is provided: {url}/entrypoints/{entrypoint}/invoke (v2)
• Otherwise: Uses {url} as-is (v1 / Discovery)
2. Makes a request (POST for v2, GET default for v1)
3. If 402 Payment Required is returned:
• Parses payment requirements
• Checks wallet balance and allowance
• Performs an infinite approval if allowance is insufficient
• Signs the payment permit (EIP-712 / TRON Typed Data)
• Retries the request with X-PAYMENT header
4. Returns the response

Prerequisites

• Wallet: A TRON private key must be available. The skill automatically looks for it in:

1. TRON_PRIVATE_KEY environment variable.
2. ~/.mcporter/mcporter.json (AIBank standard).
3. x402-config.json in the current/home directory.
• Tokens: Wallet needs USDT/USDD and some TRX for gas.
• TronGrid API Key: Required for Mainnet to avoid rate limits (TRON_GRID_API_KEY).

Tool Reference

x402_tron_invoke

Invokes an HTTP endpoint with automatic payment handling.

Modes:

1. v2 Agent Invoke (Recommended): Provide url (Base URL) + entrypoint.
• Constructs: {url}/entrypoints/{entrypoint}/invoke
• Wraps input: {"input": }
• Method: POST
2. v1 / Direct / Discovery: Provide url (Full URL) without entrypoint.
• Uses the URL as-is.
• Method: GET (default) or specified via method.
• Agent Advice: Use this mode for discovery. If url returns 404, try appending /.well-known/agent.json or /entrypoints.
3. Status Check: Provide --check or --status.
• Verifies if TRON_PRIVATE_KEY is correctly configured and outputs the associated wallet address.
• Checks if TRON_GRID_API_KEY is present (Required for Mainnet).
• Agent Advice: ALWAYS use this instead of env or echo $TRON_PRIVATE_KEY.

Example: Chat with Agent (v2 Invoke)

node dist/x402_tron_invoke.js --url https://api.example.com --entrypoint chat --input '{"prompt": "Tell me a joke"}'

(Sends POST https://api.example.com/entrypoints/chat/invoke)

Example: Agent Discovery (Direct)

1. Manifest: Fetch agent metadata.

```bash

node dist/x402_tron_invoke.js --url https://api.example.com/.well-known/agent.json

```

1. List Entrypoints: List available functions.

```bash

node dist/x402_tron_invoke.js --url https://api.example.com/entrypoints

```

Each entrypoint typically returns:

• Path: /entrypoints/{name}/invoke
• Pricing: Cost in tokens (e.g., 1000 units)
• Network: Usually nile or mainnet
• Input Schema: Expected JSON format for the input parameter

Example: Raw URL (Legacy)

node dist/x402_tron_invoke.js --url https://api.example.com/chat --method POST --input '{"prompt": "Tell me a joke"}'

Cost Reference (USDT/USDD)

Understanding 402 Responses

When payment is required, agents return:

{
  "error": "X-PAYMENT header is required",
  "accepts": [{
    "scheme": "exact",
    "network": "nile",
    "maxAmountRequired": "1000",
    "payTo": "T...",
    "asset": "T..."
  }],
  "x402Version": 1
}

The tool handles this automatically.

Supported Tokens

This tool supports TRC20 tokens compatible with the x402 protocol.

Recommended:

• USDT (Tether)
• USDD (Decentralized USD)

Security Rules for Agents

• No Private Key Output: The Agent MUST NOT print, echo, or output the TRON_PRIVATE_KEY or any other signing secret to the dialogue context.
• Internal Loading Only: The Agent should rely on the skill or underlying scripts to load the key internally.
• No Export Commands: The Agent MUST NOT execute shell commands that contain the private key as a literal string.
• Sanitized Logs: Ensure that logs or error messages do not leak the key.
• Silent Environment Checks: If you need to verify if an environment variable is set, use a "Silent Check".
• Correct: [[ -n $TRON_PRIVATE_KEY ]] && echo "Configured" || echo "Missing"
• Forbidden: echo $TRON_PRIVATE_KEY, env, printenv, set, export.
• Disabled Commands List: Do NOT use the following commands in any environment containing sensitive keys:
• env / printenv
• echo $VARIABLE_NAME
• set / export (without arguments)
• Use the Check Tool: To safely verify wallet status, use node dist/x402_tron_invoke.js --check.

❌ Negative Example (CRITICAL FAILURE)

> "I will check your private key now: echo $TRON_PRIVATE_KEY" -> STOP! This leaks the secret to the logs and UI.

✅ Positive Example

> "I will verify the wallet configuration: node dist/x402_tron_invoke.js --check" -> SAFE. Only the public address is shown.

Troubleshooting

"Private key not found"

Ensure the TRON_PRIVATE_KEY environment variable is set or a valid x402-config.json exists in the expected locations.

"Insufficient Allowance"

The tool will attempt to broadcast an infinite approve transaction. This requires TRX for gas. Ensure your wallet has TRX.

"Transaction Failed"

Check if you have enough Token balance (USDT/USDD) and TRX for gas.

Binary and Image Handling

If the endpoint returns an image (Content-Type: image/*) or binary data (application/octet-stream):

1. The data is automatically saved to a temporary file (e.g., /tmp/x402_image_...).
2. The tool returns a JSON object with:
• file_path: Path to the temporary file.
• content_type: The MIME type of the content.
• bytes: File size in bytes.
3. Important: The Agent is responsible for deleting the temporary file after it has been used.

Network Reference