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

With no annotations, the description carries full responsibility. It does disclose one behavioral trait ('No browser is launched'), but this is contradictory to the promised 'can be opened' and lacks details on side effects (e.g., does it make a network request?), error handling, or what 'ok' means. The agent cannot predict the tool's behavior reliably.

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 (one sentence), which is efficient, but it lacks essential information. It is not front-loaded with the most critical detail (what constitutes 'ok'), and the brevity comes at the cost of clarity.

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?

For a tool with 9 optional parameters, no required ones, and no output schema, the description is grossly inadequate. An agent cannot determine what input to provide, what the tool returns, or what side effects occur. The description fails to compensate for the complexity of the schema.

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. However, the tool description adds no guidance on which parameter to use or how they relate to the stated purpose. The parameters are all optional and cover diverse domains (URL, city, JSON, path), so the schema alone is insufficient for selecting the right parameter.

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 verb and resource ('check whether a URL can be opened') but immediately contradicts it with 'No browser is launched,' leaving the actual mechanism unclear. It doesn't distinguish from siblings like browser-url-ok or normalize-url, and the presence of many unrelated parameters (city, zone, json) suggests a broader purpose than URL checking, which is not conveyed.

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 given on when to use this tool versus alternatives such as browser-url-ok, normalize-url, or fetch-status. There are no conditions, exclusions, or context hints, leaving the agent to guess when this tool is appropriate.

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