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 does disclose one important trait—no browser is launched—but it omits whether a network request is made, what side effects or outputs occur, and how the URL is evaluated. This is insufficient for a tool with no annotation safety profile.

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 two terse sentences, front-loaded with the purpose and a key behavioral caveat. It contains no filler. It loses one point because the terseness contributes to the ambiguity about what 'opened' means.

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 9 optional parameters and no output schema, yet the description explains neither return values nor how to select parameters. Many schema descriptions say values are 'discarded,' but the description does not connect them to an overall purpose, leaving an agent under-informed.

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 all 9 parameters already have individual descriptions in the schema. The tool description itself adds no parameter-level meaning. Per the baseline for high schema coverage, a score of 3 is appropriate.

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 names a clear verb and resource ('Check whether a URL can be opened') and adds a differentiating detail ('No browser is launched'). However, it never defines what 'ok' actually means—whether it checks URL validity, reachability, shape, or something else—leaving ambiguity for an agent.

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 on when to use this tool instead of siblings like browser-url-ok, fetch-status, normalize-url, or web-fetch. The negative statement 'No browser is launched' implies a lightweight check, but the description does not state clear conditions or name alternatives.

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