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

With no annotations, the description must carry the behavioral burden. It discloses one behavior: 'No browser is launched.' But it fails to explain what happens with the diverse parameters (e.g., 'discarded after the shape check' for some, 'no disk access' for path). It does not state whether network calls occur, what the return value looks like, or whether side effects exist. The single sentence is far from sufficient.

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 (one sentence) and front-loaded with the primary action. However, it is too terse to be useful; it omits essential context about the parameter set and tool behavior. Conciseness without informativeness earns a middle score.

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, and no output schema. The description covers only a fraction of the tool's apparent surface area. It does not explain the role of most parameters, the expected inputs, or what 'ok' means as a result. This is severely incomplete 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?

The schema provides descriptions for all parameters (100% coverage), but those descriptions are unrelated to the stated URL-checking purpose (e.g., 'City name for a public weather hint'). The tool description adds no additional meaning to any parameter and does not clarify how the parameters relate to the tool's function. The mismatch between description and schema undermines 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 action: 'Check whether a URL can be opened.' This is a clear verb and resource. However, the input schema accepts 9 unrelated parameters (city, json, path, zone, query, etc.) that have nothing to do with checking a URL. The description does not reconcile this mismatch, so an agent cannot infer the actual purpose for most parameters. It is not a tautology, but it is incomplete and misleading.

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 alternatives like 'browser-url-ok', 'fetch-status', or 'normalize-url'. There is no mention of exclusions or conditions. An agent has no basis to decide between this and its siblings.

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