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

Annotations are absent, so the description carries the full burden. It does disclose the return behavior (host, scheme, HTTP status) and the privacy-relevant behavior 'Page content is not stored,' which is useful. However, it does not clarify that the tool likely makes a live HTTP request, how json/zone inputs behave, or whether there are side effects or authorization requirements.

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 sentences, both purposeful and front-loaded: the first states the function, the second adds a meaningful privacy guarantee. There is no filler, redundancy, or wasted wording.

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 no output schema and no annotations, the description must compensate for a 4-parameter polymorphic input schema, but it covers only the URL mode. It leaves json and zone behavior, output shape, and whether parameters are alternatives or combinable entirely unspecified, making it insufficiently complete for correct invocation.

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 adds meaning for the url parameter by linking it to the host/scheme/status output, but it adds no clarification for host, json, or zone, which appear disconnected from the stated purpose.

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 verb and resource: 'Return host, scheme, and HTTP status for a URL.' This is clear and not a tautology. However, it does not differentiate the tool from the sibling normalize-url, and it ignores the json and zone parameters, which suggest additional capabilities beyond URL citation.

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 description provides no when-to-use guidance and no exclusions or alternatives. It never references the sibling tools normalize-url, validate-json, or timezone, nor does it clarify whether url, host, json, and zone are mutually exclusive input modes. An agent must infer usage entirely from the schema and sibling names.

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