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

With no annotations, the description must carry the full behavioral burden. It only states that no browser is launched, but does not explain what network actions occur, what happens to the input parameters, or what 'can be opened' means. The parameter descriptions mention 'discarded', but the overall behavior remains opaque.

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 concise at two sentences, which is good for brevity, but it is under-specified and lacks any structure to convey necessary context. It is not verbose, but the brevity comes at the cost of essential information, so it is not appropriately sized.

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?

Given 9 parameters, no output schema, and no annotations, the description is severely inadequate. An agent cannot infer how to invoke the tool correctly, what inputs are relevant, what outputs to expect, or how it differs from the many siblings. The description fails to provide even minimal context for correct usage.

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%, giving a baseline of 3, but the schema descriptions themselves are contradictory to the tool's purpose (e.g., a git ref for checking a URL). The tool description adds no semantic clarification, and the parameter names and descriptions suggest a multi-purpose validator rather than a simple URL check, making the semantics confusing.

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') but is ambiguous about what 'opened' means and how it relates to the 9 parameters, which include unrelated fields like city, json, and zone. It does not distinguish itself from siblings like fetch-status or normalize-url, leaving the agent uncertain about its exact scope.

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. The sibling list contains many URL-related tools (fetch-status, web-fetch, normalize-url, playwright-url-ok), but the description offers no comparison or selection criteria.

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