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 'No browser is launched,' which is a negative trait, but it doesn't disclose whether a network request is made, whether it validates URL syntax, what side effects occur, or what the return value looks like. The wide parameter list further obscures behavior.

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 extremely short (two sentences), but it is under-specified rather than concise. It front-loads nothing useful and leaves out essential information. The brevity is not a virtue when it sacrifices necessary context.

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 9 parameters, no output schema, and no annotations, this description is grossly incomplete. It doesn't explain what the tool returns, how to interpret results, what side effects occur, or which parameters to use for which scenario. An agent cannot reliably call this tool based on the provided information.

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%, but the parameter descriptions themselves are disjointed (e.g., 'ref' is 'discarded after the shape check', 'city' is for a weather hint, 'json' is to validate) and do not relate to the tool's stated purpose of checking URL openness. The description adds no explanatory value beyond the schema, and the schema descriptions seem to describe a generic 'shape check' tool rather than a URL checker, 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 uses a specific verb and resource ('Check whether a URL can be opened') but is extremely vague about what 'can be opened' means (HTTP status? URL syntax? DNS?). It also fails to align with the 9-parameter schema, which includes city, zone, query, etc., suggesting the tool does far more than URL checking. This vagueness makes it hard to distinguish from siblings 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?

There is no guidance on when to use this tool versus the 28 siblings. No mention of alternatives, exclusions, or prerequisites. An agent has no way to know if this is the right tool for a URL availability check versus normalize-url, web-fetch, or browser-url-ok.

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