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PreFlight Checker — MCP Server Safety Audit
x402
PreFlight Checker — MCP Server Safety Audit is a paid API for AI agents from x402-api-catalog.onrender.com, paid per call via x402, $0.06/call, status unknown (last checked 2026-09-14).
Performs a live MCP handshake plus static analysis of every tool's name, description, and schema to detect tool-poisoning, prompt injection, and dangerous capability combinations, with optional GitHub supply-chain signal.
Price / call$0.06
Success—
StatusUnknown
How this service works
MCP server safety audit: completes a real initialize+tools/list handshake, then statically scans every tool's name/description/schema for hidden unicode (tool-poisoning), prompt-injection-style phrasing, and tools that quietly combine multiple high-privilege capabilities (network+filesystem+exec+credential access). If a GitHub repo is supplied, folds in a real software-supply-chain signal too.
Output
Returns a safety score, a verdict (e.g. pass/warn/fail), and detailed findings including any detected hidden unicode characters, prompt-injection-style phrasing in tool names or descriptions, tools that combine multiple high-privilege capabilities (network, filesystem, exec, credential access), and optionally a GitHub supply-chain signal for the linked repository.
Example use cases
Vetting a third-party MCP server
“Before I connect our agent to this MCP server at https://partner-tools.example.com, can you audit it for hidden unicode, prompt injection tricks in the tool descriptions, and any tools that quietly bundle network, filesystem, and credential access together?”
Pre-deployment security check with GitHub signal
“We're about to deploy an agent that uses https://open-source-mcp.example.com — can you run a security scan on it and also check the GitHub repo opensourcecorp/mcp-tools for any supply-chain red flags?”
Continuous trust monitoring for MCP toolchain
“I want to know if the MCP server at https://internal-tools.mycompany.com is still clean — scan it for tool-poisoning attacks or any new prompt-injection-style phrasing that might have snuck into the tool schemas since last time.”
Technical details
Endpoint
GEThttps://x402-api-catalog.onrender.com/api/mcp-auditWhen to prefer
Use this endpoint when you need to vet an MCP server before connecting an AI agent to it, especially when the server is third-party, open-source, or untrusted. It is the right choice over generic HTTP health checks because it performs a real MCP protocol handshake and specifically targets AI-agent attack vectors: tool poisoning, hidden unicode, prompt injection in schemas, and dangerous capability bundling. If you also have a GitHub repository for the MCP server, pass it to get a software supply-chain risk signal in the same call.
Side effects
- MCP server URL unreachable or not responding to initialize handshake — audit fails with connection error
- Target server does not speak streamable-HTTP MCP transport — handshake fails
- GitHub repo not found or rate-limited — supply-chain signal omitted from results
- Malformed URL input — returns validation error
- Server times out during tools/list enumeration — partial results or error returned
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"url": "https://mcp.example.com/mcp",
"score": 90,
"verdict": "healthy: no red flags found",
"findings": [],
"tools_found": 3
}
}Tags
x402
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