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

With no annotations provided, the description carries the full behavioral burden. It discloses one meaningful behavior: no browser is launched. However, it does not clarify whether the check performs network requests, whether it is purely read-only, what happens with invalid inputs, or how the given URL is evaluated, so the disclosure is only partial.

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 short sentences that immediately state the purpose and the most important non-behavior. Every word earns its place, and there is no redundant fluff.

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 absence of an output schema and annotations, the description should clarify what a successful check returns, what 'can be opened' means, and which of the nine optional parameters are relevant. It does none of these, leaving an agent to guess at the result format and evaluation criteria.

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 parameters are already documented and the description does not need to repeat their meanings. Still, the description identifies 'URL' as the core focus while the schema includes many non-URL parameters such as city, json, timezone, and query; the description does not explain how those relate to the URL check, leaving some semantic ambiguity.

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' and adds the useful caveat 'No browser is launched.' However, 'can be opened' is ambiguous—it could mean URL syntax validation, browser support, or network reachability—and the schema exposes many unrelated optional parameters, making the tool's scope less clear than it first appears.

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 phrase 'No browser is launched' weakly implies this is a lightweight preflight check rather than a full browser-based navigation, which hints at when to use it versus a sibling like playwright-url-ok. But the description never explicitly names alternatives, conditions, or exclusions, so the guidance remains implicit rather than actionable.

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