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

Annotations are absent, so the description carries full burden. It discloses that no browser is launched, but fails to explain what actually happens: how the URL is checked (HTTP request? DNS?), what 'shape check' means, or why parameters like city, json, path, zone, query are accepted and discarded. The behavior remains opaque beyond the single sentence.

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 appropriately brief (one sentence) and front-loads the main action. However, it's so sparse that it omits critical context about the tool's actual behavior and the meaning of the many parameters. It's concise but under-specified, earning a middle score.

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 9 parameters, no annotations, no output schema, and a description that mentions only URL checking, the tool is severely under-described. The 'shape check' concept and the disposal of most parameters are unexplained. The agent cannot reliably infer what the tool does for inputs like city or feed, or what the return value looks like. This is far from complete.

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 each parameter. The description adds no additional meaning to parameters; it doesn't explain how 'url' is used or what 'discarded after the shape check' concretely entails. Baseline 3 is appropriate since the schema does the heavy lifting and the description provides no extra parameter context.

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: 'Check whether a URL can be opened.' It also adds a distinguishing constraint, 'No browser is launched,' which separates it from the sibling 'browser-url-ok.' However, it doesn't explicitly mention that the tool also performs shape checks on other inputs (ref, city, feed, etc.), so it's not fully precise about the tool's broader scope.

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 explicit guidance on when to use this tool versus alternatives. It only implies the no-browser distinction, but doesn't state conditions like 'use this for quick reachability checks without rendering' or contrast with normalize-url or fetch-status. The agent would have to infer usage context from the name and siblings.

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