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

With no annotations available, the description carries the full burden of behavioral disclosure. It adds one useful privacy note, 'Page content is not stored,' but omits whether the URL is fetched, whether redirects are followed, and what side effects or requirements exist.

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?

The text is short and front-loads the core operation in the first sentence. The second sentence is a meaningful caveat, though for a tool with four optional parameters and no title, the description feels slightly too terse.

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 four-parameter tool with no annotations and no output schema, this description is incomplete. It leaves unclear how the parameters combine, when each should be used, what the response format is, and what actually happens when the tool is called.

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 applies and the description does not need to repeat parameter-level details. However, the description introduces 'host' as a return value while 'host' is also an input parameter, and it gives no hint how 'json' and 'zone' relate to the URL operation.

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 concrete verb and resource: 'Return host, scheme, and HTTP status for a URL.' It clearly communicates the core operation, but it does not explicitly differentiate this tool from sibling tools that also handle URLs and status data.

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 guidance is provided about when to use this tool versus alternatives, nor any exclusions or preconditions. The agent is left to infer the intended use case from the short description alone.

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