Check a URL's HTTP response to identify missing security headers and inspect status, redirects, and headers.
Fetch a URL and return status, redirect chain, response headers and which common security headers are missing.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It transparently states that this performs a live fetch and enumerates what is returned. It does not mention potential side effects like triggering requests on the target or rate limits, but 'Fetch a URL' makes the active network behavior clear.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single, well-structured sentence that front-loads the action and packs all key output details without wasted words. Every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a one-parameter tool with no output schema, the description covers the main behavior and return contents well. It lacks URL format expectations and error-handling notes, but these are minor for a simple HTTP header inspection tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must compensate. It only repeats the parameter name ('URL') without specifying accepted formats, whether a scheme is required, or whether IPs/domains are valid. The agent gets no additional meaning beyond the schema's 'url' string field.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific verb ('Fetch'), a concrete resource ('a URL'), and the exact outputs: status, redirect chain, response headers, and missing security headers. This clearly distinguishes it from the DNS/whois/subdomain siblings.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The purpose is clear enough that an agent can infer when to use it: whenever HTTP-level response information is needed. It does not explicitly name alternatives or exclusions, but the sibling tools are sufficiently different in domain that the intended context is obvious.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.