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

With no annotations, the description must disclose behavior fully. It only states that no browser is launched, but omits what 'can be opened' actually entails (e.g., network request vs. syntax check) and does not explain the fate of the nine parameters (many of which are unrelated). The tool's actual behavior remains opaque, especially regarding the discarded parameters mentioned in the schema.

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 concise—two short sentences with no fluff. The behavioral note about not launching a browser is front-loaded and useful. However, it is so sparse that it borders on under-specification rather than being efficiently informative.

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 9 parameters, no output schema, and no annotations, the description is grossly incomplete. It does not explain what 'can be opened' means operationally, how the parameters influence the check, or what the tool returns. An agent cannot correctly invoke this tool based on the description alone, especially with the many unrelated parameters.

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 each parameter has a brief description. The tool description adds no additional meaning beyond the schema, but the schema already covers the basics. The description does not clarify why so many unrelated parameters (city, json, path, zone, query) are present, which is a missed opportunity, but the baseline of 3 is appropriate given full schema coverage.

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 ('Check') and resource ('URL'), and adds a key qualifier ('No browser is launched') that hints at its non-browser nature. However, it does not differentiate from many siblings like fetch-status, web-fetch, or playwright-url-ok, which also deal with URL checking or fetching. The primary action is clear, but the scope is under-specified.

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 its many siblings. The description does not mention alternatives, exclusions, or conditions for selection. An agent would have to guess when to pick this over fetch-status or web-fetch, making the choice ambiguous.

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