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, yet it only reveals that no browser is launched. It does not say whether a network request is made, whether the check is purely syntactic, what side effects occur, or what the result looks like. The ambiguous phrase 'can be opened' leaves the actual behavior unclear.

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 two short sentences with no filler; it is front-loaded with the core purpose and then a clarifying behavioral constraint. It earns conciseness points, though the brevity leaves significant contextual gaps.

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 nine optional parameters and no output schema, the description is far too sparse. It does not explain the role of non-URL parameters, define what 'can be opened' means operationally, describe return values, or clarify how this tool relates to its many siblings. The schema helps but cannot compensate for the missing behavioral and usage context.

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%, and each parameter already has a specific description (e.g., 'HTTPS URL to normalize or cite', 'JSON text to validate'). The tool description adds no parameter-level meaning, so the baseline of 3 is appropriate because the schema carries the semantic weight.

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') and adds a distinguishing behavior ('No browser is launched'), which helps differentiate it from browser-url-ok. However, it only covers URL checking while the schema exposes eight other unrelated parameters (city, json, path, zone, query, etc.), so the stated scope is incomplete and somewhat 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?

The only usage signal is the negative constraint 'No browser is launched,' which implies a lightweight check but does not explain when to choose this tool over siblings like web-fetch, fetch-status, normalize-url, or browser-url-ok. There is no guidance on which of the nine optional parameters to supply or what kind of inputs are appropriate.

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