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 discloses that no browser is launched; it does not mention network behavior, side effects, what 'opened' means, or what the caller receives. For a tool with no annotation safety hints, this is a significant gap.

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 concise: two short sentences with no filler. The key behavioral caveat ('No browser is launched') is front-loaded and useful. It loses one point because it is so terse that it omits needed context for the 9-parameter schema.

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 heterogeneous parameters, no output schema, and no annotations, this description is far from complete. It does not specify return values, how 'can be opened' is determined, whether parameters are mutually exclusive, or how the listed params map to the check. The schema descriptions help but the tool description itself leaves major gaps.

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 every parameter already has a description and the baseline is 3. The tool description itself adds no parameter-level meaning and does not explain why parameters like city, feed, ref, or zone relate to checking a URL, but the schema already handles individual parameter documentation.

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' — with a clear resource (URL), and the clause 'No browser is launched' helps distinguish it from browser-based siblings like browser-url-ok. However, it does not explain what mechanism is used instead, leaving some ambiguity about what 'can be opened' means.

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?

The description gives no explicit when-to-use or when-not-to-use guidance, and it never names alternatives. The 'No browser is launched' hint implicitly separates it from browser-url-ok, but the agent is left to infer when this tool should be selected over fetch-status, normalize-url, or other URL-related siblings.

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