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

No annotations are provided, so the description carries the full burden. It discloses that no browser is launched, but does not explain what 'can be opened' means, how the check is performed, or what happens with the many other parameters (several are noted as 'discarded' in the schema). This is insufficient for a tool with no annotation coverage.

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 only two sentences, which is brief, but the brevity is not effective because it omits critical information about the tool's real scope and behavior. It is under-specified rather than concisely complete.

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?

Given the tool has 9 parameters, no annotations, and no output schema, the description is grossly incomplete. It fails to explain how the parameters are used, what the return value represents, or any constraints. An agent cannot reliably invoke this tool correctly based solely on the 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% – every parameter has a description in the schema itself, so the baseline is 3. The description adds no additional parameter meaning beyond the schema, but it doesn't need to since the schema already documents each parameter's role (even if some are 'discarded').

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') but the input schema lists 9 unrelated parameters (city, zone, json, feed, etc.) that have no obvious connection to opening a URL. This creates confusion about the actual purpose; the tool seems to be a catch-all validator rather than a URL-specific checker.

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 its siblings (e.g., browser-url-ok, normalize-url, fetch-status). There is no mention of conditions, alternatives, or exclusions, leaving the agent without direction for selection.

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