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

With no annotations, the description carries the full burden, and it does disclose the core behavior: HEAD method (lightweight, no body), public-URL-only scope, and status-only output. But it is silent on redirects, failure behavior, rate limits, and error states, and the schema's param descriptions reveal behaviors (discarding inputs, no disk access) not reflected in the description.

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?

A single front-loaded sentence with zero filler. The verb, scope, and output constraint are all present with no wasted words.

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 9-parameter tool with no annotations and no output schema, a one-sentence description covering only the URL-HEAD behavior is inadequate. It does not explain the return format, the role of the other eight parameters, or failure handling. The description is notably incomplete relative to the tool's demonstrated complexity.

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 baseline 3 applies. The description adds no parameter-level meaning, and the schema descriptions are self-sufficient. However, there is a mismatch: the description frames the tool as URL-HEAD-only while params like city, json, query, and zone describe unrelated validation behaviors, creating ambiguity about how they fit the described 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 (HEAD), resource (public URL), and result (status only), which clearly distinguishes it from web-fetch and the url-ok siblings. However, the input schema reveals the tool also handles non-URL inputs (json, city, query, zone, path, ref), which the description never mentions, so the stated purpose is narrower than the actual tool behavior.

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 when-to-use guidance, no exclusions, and no alternatives are named despite a crowded sibling field (web-fetch, browser-url-ok, playwright-url-ok, normalize-url, status-catalog). 'Return status only' weakly implies the use case, but an agent gets no help deciding between this tool and overlapping siblings.

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