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

With no annotations, the description carries the full burden. It discloses only that no browser is launched, but does not mention network access, side effects, error behavior, output format, or whether unrelated parameters are ignored.

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 very short and front-loaded with the core purpose. It is concise, though it sacrifices important detail; there is no structured breakdown of behavior or parameters.

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 tool has nine optional parameters, no output schema, and no annotations, yet the description does not explain what the tool returns, which parameters are relevant, or how the openability check is performed. Context is severely incomplete for an agent to use it reliably.

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?

Although every parameter has a description, the descriptions are mismatched with the tool's stated purpose. The 'url' parameter is described as 'HTTPS URL to normalize or cite' rather than something to check, and most other parameters (city, feed, json, path, zone, query) appear wholly unrelated to checking URL openability, creating 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 specific verb and resource ('Check whether a URL can be opened') and adds a clarifying constraint ('No browser is launched'). However, it is vague about what 'can be opened' means (HTTP status? reachability?) and does not differentiate from similar sibling tools like browser-url-ok or fetch-status.

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, what conditions make it appropriate, or how to select among the many schema parameters. The only hint (no browser launched) is a behavioral constraint, not usage direction.

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