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 does not reveal whether the tool makes network requests, what it returns, or how it handles the many parameters. The schema descriptions for some params (e.g., 'discarded after the shape check') imply side effects, but the description itself is silent, leaving behavior largely opaque.

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 concise with two sentences and front-loads the primary purpose. However, it is under-specified for a tool with nine parameters and no other metadata; brevity here sacrifices necessary context. It is not excessively verbose, but it does not earn its place as an adequate description.

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 description is grossly incomplete for a tool with 9 parameters, no output schema, and no annotations. It does not explain what the tool returns, how it behaves with different parameter combinations, or any side effects. An agent cannot reliably invoke this tool correctly based solely on this description.

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 baseline is 3, but the description adds no parameter-level meaning. More importantly, the tool's stated purpose (checking a URL) does not align with parameters like city, json, path, zone, or query, and the description does not explain why they exist. The schema descriptions are self-contained but do not reconcile with the purpose, so the description fails to add value beyond the schema and even introduces confusion.

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') and adds a distinguishing caveat ('No browser is launched'). However, it is vague about what 'can be opened' entails (network request, HTTP status, etc.) and does not differentiate from siblings like fetch-status or normalize-url. The input schema includes many non-URL parameters (city, json, path, zone, query) that contradict the narrow purpose, undermining clarity.

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 gives no guidance on when to use this tool versus alternatives. It only says 'No browser is launched,' which hints at a lightweight check but does not explicitly mention conditions, exclusions, or alternatives such as playwright-url-ok. An agent cannot infer the appropriate context for invoking this tool.

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