MCPFax URL Intelligence

What a host says about itself

url_headers

Response status, server software, content type, caching, and which of the six standard security headers the host sets or omits. Use to check a URL is live and well-formed before relying on it, or to profile a site cheaply without downloading it. Header presence is a hygiene signal, not a safety verdict — a site can set every header and still be malicious. Costs $0.005 USDC per call via x402 on Base.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "url": "<url>"
    },
    "name": "url_headers"
  }
}

Input Schema

Name	Required	Description	Default
`url`	Yes	The URL to inspect.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 4, 2026
- addedInput schema / properties / url / examples
```
Added value: +[
+  "https://example.com"
+]
```
First observedSep 1, 2026

TDQS

A4.1/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the behavioral burden. It goes beyond the basic fetch by disclosing the cost per call ($0.005 USDC via x402 on Base) and adding an important interpretive caveat that header presence is a hygiene signal, not a safety verdict. This is meaningful behavioral and risk context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Four sentences, each earning its place: output inventory, use cases, safety caveat, and cost. The most important scoping information is front-loaded, and there is no redundant or filler text.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple one-parameter tool with no output schema and no annotations, the description covers selection, invocation, cost, interpretation, and limitations. An agent has enough context to decide when to call it and what to expect without needing additional documentation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, and the schema already documents the single 'url' parameter with examples and a clear description. The tool description adds little beyond implying the URL should be well-formed, so the baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the tool's purpose by enumerating what it returns: response status, server software, content type, caching, and security headers. It implies a fetch/inspect operation on a URL without naming a sibling alternative, but the resource and output are specific enough to distinguish it from the sibling list.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives explicit use cases: checking whether a URL is live and well-formed before relying on it, and cheaply profiling a site without downloading it. It does not state when not to use it or name alternative tools, so it falls short of a 5, but the context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All MCPFax URL Intelligence tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?