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

With no annotations, the description carries the full burden of behavioral disclosure. The only behavioral note is 'No browser is launched,' which clarifies it is not a full browser operation. But it does not explain what 'opened' means, whether it makes network requests, what side effects occur, or what happens with the many parameters that are described in the schema as 'discarded.' This is insufficient for a tool with this complexity.

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 terse—a single sentence—which is not appropriate for a tool with 9 parameters and no output schema. It under-specifies the tool's behavior and leaves the agent without sufficient information. While conciseness is valued, here it sacrifices necessary detail.

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 complexity (9 parameters, no annotations, no output schema, many sibling tools), the description is severely incomplete. It does not explain what 'opened' means, what the return value is, which parameters are required, or how this differs from similar tools. An agent cannot confidently invoke this tool correctly based on the description alone.

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?

The schema descriptions provide 100% coverage and are fairly detailed (e.g., 'Git ref name; discarded after the shape check'). The tool description adds nothing about parameters beyond what the schema already states. Given the high schema coverage, the baseline of 3 is appropriate, but the description does not help map which parameter is the primary URL or how they relate to the tool's purpose.

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 action ('Check whether a URL can be opened') and includes a distinguishing note ('No browser is launched'). However, the input schema lists 9 unrelated optional parameters (city, zone, json, path, etc.) that do not clearly map to URL checking, making the tool's actual scope ambiguous. It also does not differentiate from sibling tools like playwright-url-ok or fetch-status, which likely have overlapping purposes.

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 guidance on when to use this tool versus the many sibling tools. No context, prerequisites, or alternative recommendations are provided. The description only states what it does, not when it is appropriate.

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