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

With no annotations, the description carries the full disclosure burden and does offer one useful trait: 'Page content is not stored.' But it never explains that the tool can perform multiple unrelated checks (shape, length, JSON validation, timezone, weather hints) and what side effects or return values accompany those paths, leaving the agent to infer behavior from the schema alone.

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 tight sentences with no filler; the primary behavior is front-loaded and the privacy note earns its place. The brevity is earned, though for a nine-parameter tool this economy comes at the cost of missing information (captured under contextual completeness).

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 tool has nine optional parameters spanning unrelated domains, no output schema, and no annotations, yet the description explains only the URL case and omits what the other seven parameters do, how results are returned, and how the tool relates to overlapping siblings. An agent cannot reliably predict behavior for the non-URL inputs.

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 baseline of 3 applies; each parameter has a terse but understandable schema note (e.g., 'discarded after the shape check'). The description adds no parameter-level meaning beyond the one 'url' parameter it implies, so it neither helps nor hurts beyond the schema.

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 states a specific behavior — 'Return host, scheme, and HTTP status for a URL' — which is a clear verb+resource. However, the input schema exposes nine unrelated parameters (weather city, RSS feed, JSON text, IANA zone, file path, search text), so the stated purpose covers only a fraction of the tool's actual surface and does not differentiate it from siblings like fetch-status or normalize-url.

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?

No when-to-use guidance is given and no alternatives are named; an agent cannot tell when to pick this over fetch-status, normalize-url, browser-url-ok, or web-fetch. The eight non-URL parameters are never explained in the description, so there is no context for when they would be relevant.

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