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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only states that no browser is launched, but it omits other important behaviors such as whether a network request is made, side effects, return format, or failure modes. This is insufficient 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 extremely concise (two short sentences) with no wasted words, which is structurally efficient. However, the brevity borders on under-specification given the tool's complexity (9 parameters, no output schema). It is concise but not effectively so, as it omits necessary context.

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 optional parameters, no output schema, and no annotations, yet the description provides only a vague two-sentence explanation. It fails to explain what the tool returns, how to interpret 'ok', how to use the mixed set of parameters, or any edge cases. This is completely inadequate for an agent to call it correctly.

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 coverage is 100%, so the baseline is 3. However, the description does not add any semantic value beyond the schema; it refers only to URLs while the schema contains many unrelated parameters (city, json, path, zone, query) that are not explained in the description. This creates confusion about how the parameters relate to the stated purpose, so the description actually detracts from parameter understanding.

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 specific verb and resource ('Check whether a URL can be opened') which is clear on its face. However, it does not differentiate from sibling tools like normalize-url or fetch-status, and the meaning of 'opened' is ambiguous (syntactic validity vs. network reachability). The description also seems inconsistent with the input schema, which includes unrelated parameters like city, json, and zone, making the purpose less clear in context.

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 explicit usage guidance is given. The phrase 'No browser is launched' implies a lightweight check, but it does not mention when to choose this tool over alternatives like playwright-url-ok or fetch-status, nor does it state any prerequisites or when not to use it. The guidance is implicit at best.

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