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

Annotations are absent, so the description carries the full burden of behavioral disclosure. It states only that page content is not stored, which is a useful privacy note, but it does not disclose that most parameters are discarded after validation, that there is no disk access, or what the tool does with the other eight parameters. The schema descriptions mention 'discarded' for several fields, but the description itself fails to explain the overall behavior for non-URL inputs. This is a significant gap for a tool with such a diverse schema.

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 description is a single sentence, which is very concise and front-loaded with the main function. However, given the tool's complexity (nine parameters, many seemingly unrelated), this brevity is under-specification rather than effective conciseness. It omits essential information about the tool's scope and behavior, making the short length a liability rather than a strength.

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, no output schema, and no annotations, yet the description only covers the URL-based outcome. It does not explain what happens with the other parameters, why they exist, or how they relate to the main function. This leaves an agent uncertain about whether to pass them or what to expect. For a tool with this complexity and no structured annotations, the description is clearly incomplete.

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 is 3. The description does not add any meaning beyond the schema for the parameters. It only mentions 'url' implicitly through 'a URL,' but does not clarify the role of the other eight parameters, many of which are marked as discarded. This creates confusion about whether they are relevant to the output. The schema provides individual parameter descriptions, but the description does not synthesize them into a coherent semantic model.

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 and resource: 'Return host, scheme, and HTTP status for a URL.' It is unambiguous about the primary action. However, it does not differentiate from sibling tools like fetch-status or normalize-url, which likely perform similar URL operations. The presence of nine unrelated parameters in the schema further muddies the purpose, but the core function is clear.

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 given on when to use this tool versus its siblings. The sibling list includes tools like fetch-status, normalize-url, domain-shape, and others that may overlap significantly. The description does not mention any alternatives or specify conditions for selection, leaving the agent to infer usage context.

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