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 does state 'Body discarded,' which is a useful behavioral detail, but it omits critical information such as whether the tool makes network requests, follows redirects, returns only status codes or also headers, and how the other parameters behave. It also fails to disclose that the tool handles multiple check types beyond URLs, making it appear simpler than it is.

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 and front-loaded: two short sentences. It does not waste words, and the key idea (status/content type, body discarded) is placed early. However, its brevity comes at the cost of completeness, though that is a separate dimension. Structurally, it is efficient.

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 annotations, and no output schema, so the description must carry a heavy informational load. It fails almost entirely: it addresses only one of many use cases, provides no indication of the other check types, and offers no output format or error behavior. An agent would be severely under-informed about how to invoke this tool correctly for any non-URL parameter.

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%, so the baseline is 3, but the description adds no value for parameters and actually misleads by implying only 'url' is relevant. The schema already documents each parameter, but the description does not clarify that the tool performs distinct checks (JSON validation, timezone, path, etc.). It fails to compensate for the lack of overall context.

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 clearly states the primary purpose for the url parameter ('HTTP status and content type for a public URL'), but it ignores the other eight parameters (ref, city, feed, host, json, path, zone, query) that the schema supports. As a result, it only conveys a fraction of the tool's actual purpose, leaving an agent with an incomplete and somewhat misleading understanding.

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 its many siblings (e.g., fetch-status, browser-url-ok, normalize-url). The description does not mention alternatives, conditions, or exclusions, leaving the agent to guess which tool fits a given scenario.

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