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

Goes well beyond the readOnlyHint/openWorldHint annotations: discloses that warnings are emitted for credentials, plain http and punycode, that passwords are never echoed, and that billing is 1 credit per successful call with schema-invalid input rejected before billing. That is exactly the kind of rate/cost and safety detail an agent needs.

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?

Front-loaded with the operation and its components, then the return shape and cost. Slightly redundant in listing the parsed components and then repeating them in the returned object, but every sentence carries information.

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, the description compensates by enumerating the full returned object and the warning behavior, plus cost and rejection semantics. An agent has everything needed to call it and interpret the result.

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 coverage is 100% with a single required 'url' parameter already described as an absolute URL that is not fetched. The description adds nothing about format, length limits, or edge cases beyond the schema, so the baseline of 3 applies.

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?

States a precise verb and resource: 'Splits a URL into scheme, host, port, path segments, query ... and fragment', with the exact output shape enumerated. An agent knows exactly what transformation happens. It does not name or differentiate from the closest siblings (enrich-url, og-preview, web-extract), so it stops short of a 5.

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?

There is no explicit statement of when to use this versus alternatives like enrich-url or og-preview, and no exclusion conditions. The only usage cue is the schema note 'It is not fetched', which implies offline parsing but is not framed as guidance.

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