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 reveals that no browser is launched, but does not state whether the tool makes network requests, checks DNS, validates URL syntax, or has side effects. Additionally, the input schema includes parameters like 'city', 'zone', 'query', and 'json', which are unrelated to a URL check, suggesting the tool may perform multiple kinds of checks—yet the description does not explain this. This creates confusion about the actual behavior.

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—a single sentence—which is efficient. However, it is not front-loaded with key information; it only states the action and a single qualifier. Given the tool's complexity (9 parameters), the description is too sparse to be considered well-structured. It earns its place but does not provide a useful hierarchy or context.

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 parameters, no output schema, and no annotations. The description is a single vague sentence that does not explain the return value, side effects, or the relationship between the 'URL' purpose and the other parameters. It is far from complete for an agent to understand what this tool does, when to call it, and what to expect. The description is insufficient for safe and correct invocation.

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 the schema already documents every parameter. The tool description adds no parameter-specific information, so it does not improve upon the schema. The baseline of 3 is appropriate because the schema does the heavy lifting; the description does not need to repeat it. However, the schema descriptions themselves are odd (e.g., 'discarded after the shape check'), but that is outside this dimension's scope.

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 ('Check') and resource ('URL'), and adds a clarifying note ('No browser is launched') that distinguishes it from browser-based tools. However, the phrase 'can be opened' is vague—it does not specify whether this is a format validation, DNS lookup, HTTP status check, or something else. The scope is unclear, and it does not differentiate from siblings like fetch-status or normalize-url.

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 provides no guidance on when to use this tool versus alternatives. It does not mention any sibling tools, prerequisites, or conditions for selection. The only hint is 'No browser is launched,' which suggests it is lighter-weight than playwright-url-ok, but that is implicit. There is no explicit when-to-use or when-not-to-use information.

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