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

With no annotations, the description carries the full burden. It discloses exactly one behavioral trait ('No browser is launched'), which is valuable given the Playwright name, but it does not explain whether the tool performs an actual network request, what 'can be opened' means (HTTP status, DNS resolution, etc.), what the return value is, or how the many non-URL parameters are handled.

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?

Two short sentences, front-loaded with the primary action ('Check whether a URL can be opened') followed by a key limitation ('No browser is launched'). Every word earns its place, with no filler or redundancy.

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 tool has a complex seven-parameter schema, no output schema, and many near-sibling tools (browser-url-ok, web-fetch, fetch-status, normalize-url, validate-json). The description only addresses URL checking and does not clarify return semantics, the meaning of 'opened', how the other parameters relate, or how to choose this tool over siblings.

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% — each of the seven parameters has a description (e.g., 'Git ref name; discarded after the shape check'). The tool description adds no parameter-level meaning, but the baseline of 3 applies because the schema already documents each parameter.

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 specific verb and resource ('Check whether a URL can be opened') and adds a distinguishing behavioral trait ('No browser is launched') that separates it from browser-based sibling tools. However, it does not explicitly name a sibling or explain how it differs from browser-url-ok, and the broad input schema with city, ref, json, and path parameters is not reflected in the stated purpose.

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 'No browser is launched' line gives an implied usage context: use this for lightweight URL checks without browser overhead. But there is no explicit when-to-use guidance, no mention of prerequisites, and no exclusions naming alternatives like browser-url-ok or web-fetch.

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