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

With no annotations, the description carries the full burden of behavioral disclosure. It does add one meaningful behavior: query and fragment are dropped. However, it fails to clarify the role of the extra schema fields (host, json, zone), whether they are ignored, or what happens with invalid or missing input.

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 tight sentences with no filler. The main action is front-loaded, and the behavioral caveat about query and fragment earns its place. It is appropriately sized for a simple URL utility.

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?

Given no annotations, no output schema, and a schema containing four unrelated-looking parameters, the description is too thin. It does not state that only 'url' is used, nor does it clarify that host, json, and zone are irrelevant or ignored. An agent could reasonably pass the wrong parameters or call the tool with no arguments, since no parameters are required in the schema.

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 much beyond the schema regarding parameter meaning; it implies 'url' is the relevant input but does not address host, json, or zone. The schema already documents those fields, so no additional penalty is warranted.

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 concrete action and resource: 'Return origin, host, and path for a URL.' It adds precision by noting query and fragment are dropped. It does not explicitly distinguish itself from sibling tools, but the intended function is fairly distinct from domain-shape, inspect-robots, or validate-json.

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 gives no guidance on when to use this tool versus alternatives like domain-shape or inspect-robots, and it does not mention any exclusions or prerequisites. It only describes what the tool does, not when it is appropriate.

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