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

With no annotations, the description carries the full burden. It discloses that no browser is launched, which is valuable, but it omits other key behavioral traits such as whether any network access occurs, possible timeouts or errors, or side effects. The schema param comments (e.g., 'no disk access') hint at safety, but the description itself is minimal.

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?

Two short sentences state the purpose and a critical behavioral clarification. Every word earns its place, and the key information is front-loaded.

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 9 heterogeneous parameters and no output schema or annotations. The description does not explain how the parameters relate to the URL check or what the return value indicates. An agent would need to infer behavior from the name and sibling set, which is insufficient for this level of complexity.

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%, so all 9 parameters already have meaning in the structured data. The description itself adds no parameter-specific semantics beyond the schema, so a baseline 3 is appropriate.

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 gives a specific verb and resource: 'Check whether a URL can be opened.' The phrase 'No browser is launched' partially distinguishes it from browser-based sibling tools, but it does not explicitly name any sibling or define the boundary precisely, so it is clear but not fully differentiated.

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 alternatives like browser-url-ok, normalize-url, or fetch-status. No when-not-to-use instructions or exclusions are given. The only behavioral note, 'No browser is launched,' implies a lightweight check but does not state which kind of check to choose it for.

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