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

With no annotations, the description must carry the burden. It does disclose one behavioral trait: query and fragment are dropped. However, it does not mention how the other parameters (ref, city, feed, etc.) are handled, despite their schema descriptions stating they are discarded. This partial disclosure is useful but incomplete 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 a single sentence with no fluff, and the core function is front-loaded. However, given the tool's complexity (9 parameters), the brevity may under-specify the overall behavior. It is concise but not overly detailed, which earns a 4 rather than a 5.

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 description is far from complete for a tool with 9 parameters, no output schema, and no annotations. It only covers the URL normalization aspect and ignores the other parameters, which likely represent distinct functionalities (e.g., timezone, validation, hints). An agent cannot infer when to use this tool for those other purposes, so significant context is missing.

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 schema already documents all 9 parameters with clear semantics (e.g., 'Git ref name; discarded after the shape check'). The tool description adds no parameter-specific information beyond what the schema provides, so the baseline of 3 applies. It does not compensate for the schema's comprehensive descriptions.

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 verb and resource: 'Return origin, host, and path for a URL.' This is specific and aligns with the tool name. It does not, however, address the tool's other apparent functions implied by the 8 additional schema parameters, so it is not fully comprehensive. It still distinguishes from URL-checking siblings like browser-url-ok or fetch-status.

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 guidance on when to use this tool versus alternatives such as web-fetch, browser-url-ok, or domain-shape. The description only states what it does for a URL, with no mention of when it is appropriate, what prerequisites exist, or when to choose a different tool. No exclusions or alternative routing are provided.

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