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 discloses that no browser is launched, which is useful, and for several parameters it notes that values are 'discarded after the shape check' or similar. However, it does not explain what the tool actually returns, how it handles invalid inputs, or why the URL-focused description coexists with parameters for city, timezone, JSON, etc. This leaves significant ambiguity about the tool's side effects and output format.

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 extremely concise: two sentences, front-loaded with the core purpose and a key behavioral note. There is no fluff, and it quickly conveys the essential operation. It is appropriately sized for its content, even if that content is incomplete.

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 the tool's complexity (9 optional parameters, no annotations, no output schema), the description is grossly incomplete. It only addresses URL checking while ignoring the other parameters entirely, and it provides no information about return values, error handling, or how parameters interact. An agent would be unable to determine how to use this tool for anything beyond a trivial URL validity check, and the presence of unrelated parameters creates confusion rather than clarity.

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?

The schema provides descriptions for all 9 parameters (100% coverage), so each parameter is individually documented. The tool description adds no additional semantic meaning to these parameters; it does not explain how they relate to the URL check or why they are present. Since schema coverage is high, a baseline of 3 is appropriate; the description does not elevate understanding beyond the schema.

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 purpose: check if a URL can be opened, with the notable caveat that no browser is launched. This distinguishes it from siblings like playwright-url-ok (which likely launches a browser) and fetch-status (which fetches content). However, the input schema contains nine parameters, most unrelated to URLs (city, feed, json, path, zone, query), which suggests the tool actually performs a broader 'shape check' on various input types. The description does not acknowledge this mismatch, so an agent may be misled about the tool's full capabilities.

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 its siblings. The description does not mention alternatives like playwright-url-ok or fetch-status, nor does it explain the conditions under which this lightweight check is preferred. The only hint is 'No browser is launched,' which implies a non-heavyweight option, but it is not explicit or comparative.

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