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

With no annotations, the description carries the full burden of behavioral disclosure. It mentions 'No browser is launched' but fails to explain what the check actually entails (HTTP request, DNS lookup, format validation). The presence of parameters like city, zone, and query that are 'discarded' suggests a broader shape-check tool, contradicting the narrow 'URL' framing, making behavior unclear.

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 concise—two sentences with no waste. The main purpose is front-loaded, and the clarifying note about browser launch is added. It's efficient, though it could arguably be longer to cover critical gaps.

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 annotations, and no output schema, the description is severely incomplete. It doesn't explain what 'opened' means, what the tool returns, how non-URL parameters are handled, or why they are discarded. An agent cannot confidently call this tool correctly 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?

Schema coverage is 100%, so the baseline is 3. The description adds no parameter-level meaning beyond the schema; it doesn't clarify how parameters like city, zone, or query relate to the URL check. Since the schema already documents each parameter, the description provides no additional semantic value.

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 clearly states the tool's purpose: checking whether a URL can be opened, and explicitly notes that no browser is launched. This differentiates it from browser-url-ok, though 'opened' is somewhat ambiguous (syntax vs. HTTP reachability).

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 on when to use this tool versus alternatives like fetch-status, normalize-url, or browser-url-ok. The only hint is 'No browser is launched,' which implies use when browser launch is undesired, but it doesn't explicitly mention alternative tools or conditions for selection.

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