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

Annotations are absent, so the description carries the burden. It adds one useful behavioral guarantee ('Page content is not stored'), which signals a privacy-safe read operation. However, it does not disclose whether a network fetch occurs, what side effects exist, or how errors are handled.

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 the primary return behavior front-loaded and the privacy guarantee as a single clarifying second sentence. No filler or redundancy.

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?

With nine optional-looking parameters, no required fields, no output schema, and no mention of which parameter is actually needed, the description is incomplete for invocation. An agent cannot tell whether 'url' must be supplied or how the returned host, scheme, and HTTP status are represented.

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?

The input schema already describes all nine parameters with 100% coverage, including explicit notes that many are 'discarded after' the check. The description adds no parameter-specific meaning beyond naming 'URL', so the baseline score of 3 is appropriate.

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 clearly states a specific verb ('Return') and resource ('URL'), and names the three outputs: host, scheme, and HTTP status. It does not explicitly differentiate from overlapping siblings like fetch-status or normalize-url, so it loses the top score.

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?

There is no guidance about when to use this tool versus siblings such as fetch-status, normalize-url, or web-fetch. No exclusions, prerequisites, or alternative tool names are mentioned, so an agent must infer the right context.

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