402shield
x402 payment security and pre-execution transaction risk screening for autonomous AI agents.
Should I use this
Quality & Safety
Based on automated analysis of tool definitions and protocol compliance.
Context Cost
This is the approximate number of tokens consumed each time the server's tools are loaded into a model's context. Higher counts reduce the attention available for other tasks.
Install
One-Click Install
Add this to your `claude_desktop_config.json` file:
{
"mcpServers": {
"402shield": {
"url": "https://four02shield.onrender.com/mcp"
}
}
}Remote endpoints
https://four02shield.onrender.com/mcpstreamable-httpWhat it can do
Tool inventory
Tools (1)
🟡preflight_payment(requested, requestId, expected, policy, transaction, ...)
Prepare the exact paid 402Shield request that must be completed before an autonomous payment executes. Submit the returned POST request with an x402-capable client. The paid response is ALLOW, REVIEW, or BLOCK. Execute the intended payment only after ALLOW; REVIEW and BLOCK should stop execution by default. Price: $0.005 USDC.
Input Schema
{
"type": "object",
"properties": {
"requested": {
"type": "object",
"properties": {
"amountUsd": {
"type": [
"string",
"number"
]
},
"recipient": {
"type": "string"
},
"network": {
"type": "string"
},
"asset": {
"type": "string"
},
"tokenAddress": {
"type": "string"
}
},
"required": [
"amountUsd",
"recipient",
"network",
"asset"
]
},
"requestId": {
"type": "string"
},
"expected": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"policy": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"transaction": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"expectedTransaction": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"transactionPolicy": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"simulateTransaction": {
"type": "boolean"
}
},
"required": [
"requested"
],
"$schema": "https://json-schema.org/draft/2020-12/schema"
}Output Schema
{
"type": "object",
"properties": {
"service": {
"type": "string",
"const": "402Shield"
},
"action": {
"type": "string",
"const": "execute_x402_request"
},
"method": {
"type": "string",
"const": "POST"
},
"url": {
"type": "string"
},
"price": {
"type": "string",
"const": "$0.005"
},
"network": {
"type": "string"
},
"contentType": {
"type": "string",
"const": "application/json"
},
"body": {
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {}
},
"paymentRequired": {
"type": "boolean",
"const": true
},
"expectedDecisionValues": {
"type": "array",
"items": {
"type": "string",
"enum": [
"ALLOW",
"REVIEW",
"BLOCK"
]
}
},
"executionRule": {
"type": "string"
},
"advisory": {
"type": "boolean",
"const": true
}
},
"required": [
"service",
"action",
"method",
"url",
"price",
"network",
"contentType",
"body",
"paymentRequired",
"expectedDecisionValues",
"executionRule",
"advisory"
],
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false
}Community
Evidence