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

The only disclosed behavior is 'No browser is launched,' which adds one useful constraint. However, it does not explain what 'can be opened' actually means (static check? DNS? HTTP status?), what side effects or side effects are absent, what happens to inputs, or whether there are rate limits. With no annotations, the description carries the full burden and does not meet it.

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, no redundant words. The 'No browser is launched' sentence adds a distinct behavioral detail. But the under-specification limits usefulness.

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?

Despite a surface-simple schema, the tool definition is incomplete: no annotations, no output schema, seven optional parameters with ambiguous semantics, and a description that does not explain the actual behavior or return value. An agent cannot reliably decide when to call this tool or what to expect from it.

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?

All seven parameters in the schema have descriptive text, so schema coverage is 100%. The description itself adds no parameter-level meaning and does not clarify which parameter is primary or how the non-URL parameters relate to the stated purpose.

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 verb and resource ('Check whether a URL can be opened'), but the input schema includes multiple non-URL parameters (city, feed, json, path, ref) with descriptions about shape checks and discarding, which conflicts with the single-purpose reading. It does not differentiate from siblings like normalize-url or fetch-status, aside from the 'No browser is launched' note.

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 guidance on when to use this tool instead of alternatives like browser-url-ok, normalize-url, or web-fetch. There is no mention of prerequisites, exclusions, or intended context.

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