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

With no annotations provided, the description carries the full behavioral disclosure burden. It discloses only that no browser is launched, but does not state whether a network request is made, whether the operation is read-only, what failure modes exist, or what the returned result looks like.

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 very short and free of filler. The two sentences each add information: the core purpose and a key behavioral caveat. It is appropriately front-loaded, though more structural detail about return behavior and parameter usage would help.

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?

This tool has 9 parameters, no annotations, and no output schema, yet the description explains almost none of the operational context. An agent cannot determine what result to expect, which parameter is relevant for a given request, or how this relates to sibling URL-checking tools.

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 baseline is 3. Every parameter is individually described in the schema, including discard behavior, so the tool description does not need to repeat parameter meaning. It adds no parameter-level detail beyond the URL focus, but the schema already covers that ground.

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 uses a specific verb and resource: 'Check whether a URL can be opened.' The added phrase 'No browser is launched' gives a distinguishing behavioral detail, especially relative to the sibling browser-url-ok. However, 'can be opened' is somewhat vague about whether this is URL syntax validation, an HTTP reachability check, or something else.

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 explicit guidance about when to use this tool versus siblings like browser-url-ok, normalize-url, fetch-status, or web-fetch. The 'No browser is launched' phrase offers a hint, but no alternatives or selection conditions are named.

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