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

With no annotations, the description carries the full behavioral burden. It discloses that no browser is launched, but it does not explain how the URL is checked (e.g., HTTP request, DNS lookup), what the return value is, or how failures are handled. The tool also accepts 9 unrelated parameters, yet the description does not clarify why or what happens to them, leaving major behavioral gaps.

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, tightly written sentence that states the core purpose and a key constraint. It is efficient and front-loaded, with no redundant wording. However, the extreme brevity is not justified given the tool's complexity; 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?

This tool has 9 parameters, no annotations, no output schema, and many sibling tools, yet the description is just one sentence. It fails to explain what the tool does with the non-URL parameters, what output it produces, when it should be used, or how it differs from alternatives. For a tool with this complexity, the description is severely incomplete.

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?

Although schema description coverage is 100%, the descriptions are cryptic (e.g., 'discarded after the shape check') and the tool description adds no clarification about how parameters relate to the stated purpose of checking a URL. Many parameters (ref, city, feed, json, path, zone, query) appear irrelevant to a URL check, and the description does not explain their role, leaving the agent confused about which parameters are actually needed.

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 clearly states the tool checks whether a URL can be opened, with the explicit addition that no browser is launched. This gives a specific verb and resource. However, it does not differentiate it from siblings like 'browser-url-ok' or 'fetch-status' beyond the no-browser note, which is an implicit distinction rather than an explicit one.

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 description offers no guidance on when to use this tool versus alternatives. It does not mention any sibling tools, prerequisites, or scenarios where this tool is preferred. An agent has no basis for selecting it over similar tools.

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