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

With no annotations, the description carries the full burden, and it does add one useful behavioral disclosure: 'Page content is not stored,' which addresses a privacy concern. However, it does not disclose error behavior, HTTP method used, return format, or what happens for non-HTTP URLs.

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?

Two short sentences with no filler; the core purpose is front-loaded and the privacy note earns its place. It is efficient, though it could have used the second sentence to clarify the other parameters instead.

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?

The description covers only the URL-checking behavior while the schema exposes three additional parameters (host, json, zone) whose purpose is never connected to the described behavior. With no output schema and no annotations, an agent lacks enough context to understand the tool's full interface or its return format.

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 100%, so the schema documents all four parameters (url, host, json, zone). The description adds context for the url parameter via the host/scheme/status outputs, but it does not explain how the host, json, or zone parameters relate to the stated purpose, leaving their role ambiguous.

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 uses a specific verb ('Return') and names concrete outputs (host, scheme, HTTP status) for a URL, making the tool's core purpose clear. It differentiates from siblings like port-status and validate-json by listing its specific output fields, though it does not explicitly name any alternative tool.

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 statement implies when to use this tool: when an agent needs a URL's host, scheme, or HTTP status. However, it provides no explicit guidance about when not to use it or which sibling tool to prefer (e.g., normalize-url), leaving the routing decision to inference.

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