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

With no annotations, the description must carry the full burden of behavioral disclosure. It does reveal that query and fragment are dropped, which is useful, but it completely ignores the other eight parameters in the schema. The param descriptions indicate many are 'discarded', but the tool description does not explain the overall behavior for non-URL inputs, leaving the agent uncertain about side effects or return formats. This is insufficient for a tool with such a broad 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 two sentences, concise, and front-loaded with the core action. It wastes no words. However, given the complexity of the schema (9 parameters), it is arguably too terse and omits crucial information about the other parameters, making it slightly underwhelming despite its efficiency.

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 tool with 9 parameters, no annotations, and no output schema, the description is markedly incomplete. It only addresses the URL use case and ignores the other parameters, leaving the agent without understanding how to treat inputs like city, zone, json, or feed. The description fails to explain the tool's overall scope or what happens when non-URL parameters are supplied, making it inadequate for reliable 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 every parameter is individually described. The tool description adds specific meaning to the 'url' parameter (origin, host, path, query/fragment dropping) that goes beyond the schema. However, it adds nothing for the other eight parameters, which are already described in the schema. Since the schema handles the basic semantics and the description enriches only one parameter, a baseline 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 states a clear action ('Return origin, host, and path for a URL') with a specific resource and outcome. It is not a tautology and distinguishes itself from sibling checker tools like browser-url-ok or domain-shape by focusing on extraction rather than validation. However, it does not explicitly compare itself to alternatives, so it lacks sibling differentiation despite obvious intent.

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 on when to use this tool instead of the many URL-related siblings (e.g., browser-url-ok, fetch-status, web-fetch). The description implies URL normalization but never states exclusions or alternative conditions. An agent is left to infer that this is for extracting components, which is not explicit enough given the crowded sibling set.

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