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 only mentions a HEAD request and status-only return, but does not explain how the other parameters are used, whether they trigger distinct operations, or any side effects. The schema's 'discarded' notes are not mentioned in the description, so an agent cannot infer the behavior for non-URL inputs.

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 one sentence and front-loaded, which is concise, but it is under-specified for a tool with 9 parameters. It is not harmful, but it omits crucial details, making it inadequately concise rather than efficiently informative.

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 parameters, no annotations, and no output schema, this description is grossly inadequate. It does not explain the tool's multi-purpose nature, what happens for non-URL inputs, or what the return format is. Agents would be unable to call it correctly for most parameters.

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 textual explanation. The tool description adds no parameter-specific information, relying entirely on the schema. Baseline 3 is appropriate given the high coverage.

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 ('HEAD a public URL and return status only'), but the schema lists 9 unrelated parameters (timezone, JSON, city, etc.), suggesting a much broader purpose. This narrow focus does not capture the tool's actual scope and may mislead an agent into thinking it only handles URLs.

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 is given on when to use this tool versus siblings like web-fetch, browser-url-ok, or validate-json. The description provides no conditions, alternatives, or exclusions, leaving selection to chance.

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