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 does disclose a key trait: no browser is launched. However, it does not explain whether a network request is made, what kind of checks are performed, or whether any side effects occur. The disclosure is helpful but incomplete.

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 appropriately short and front-loaded: 'Check whether a URL can be opened' comes first, and the clarifying constraint 'No browser is launched' follows immediately. It is not bloated, though it may be too sparse given the tool's many 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 definition is incomplete for an 8-parameter tool with no annotations and no output schema. It does not state what 'ok' means, what the tool returns, or how the non-URL parameters are used. An agent cannot confidently call this tool correctly across its possible inputs based on the description alone.

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 description adds no parameter-level detail beyond mentioning 'URL.' The input schema already provides descriptions for all eight parameters, so baseline 3 is appropriate. Still, the description does not clarify how parameters like ref, city, json, or path relate to the core 'URL can be opened' behavior, leaving semantic gaps.

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 and resource: 'Check whether a URL can be opened.' This is clear and the 'No browser is launched' clause distinguishes it at least from browser-launching tools. However, it does not explicitly differentiate it from siblings like fetch-status or normalize-url, and the meaning of 'can be opened' is left somewhat vague.

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 about when to use this tool instead of alternatives. The phrase 'No browser is launched' is a behavioral constraint, not a selection rule, and no sibling tools or conditions are mentioned. An agent must infer the intended use case without explicit direction.

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