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

Annotations are absent, so the description must carry the full burden of disclosing behavioral traits. It does note 'No browser is launched,' which is a useful negative statement, but it does not explain what the tool actually does (network request, validation, etc.), what it returns, or any side effects. This is a significant gap for a tool with no annotation support.

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 a single vague sentence that is under-specified rather than concise. It fails to front-load key details (such as the scope of parameters or what constitutes a successful check) and provides barely any information for an agent to act on.

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 parameters, many appearing unrelated to URL checking (e.g., city, feed, json, path, zone), and no output schema. The description does not explain why these parameters exist or how they relate to the stated purpose. This is severely incomplete for an agent to understand the tool's full behavior or anticipate its response.

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 schema already documents all parameters individually. The description adds no extra meaning or context about how the parameters relate to the tool's purpose. Baseline 3 is appropriate because the schema does the heavy lifting, but the description offers no added value beyond the schema.

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'), which gives a basic action. However, it lacks specificity about what 'opened' means (HTTP status, DNS resolution, etc.) and does nothing to differentiate from sibling tools like browser-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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention conditions, exclusions, or suggest any sibling tool as a better fit for certain scenarios. An agent has no basis for selecting this tool over the many similar ones in the sibling list.

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