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

With no annotations, the description must fully disclose behavior. It only says 'HEAD a public URL' and does not mention that other parameters are discarded or that the tool performs various shape checks. It also fails to mention side effects, permissions, or the fact that it likely returns only a status code. The description is misleading because it implies URL-only behavior while the schema includes unrelated fields.

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 a single short sentence with no wasted words, which is efficient in isolation. However, for a tool with 9 parameters and many siblings, it is severely under-specified. It is concise but not appropriately sized; it omits essential context that would justify its length.

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 the tool's complexity (9 optional parameters, no output schema, numerous siblings), the description is grossly incomplete. It only explains a narrow URL-status scenario and provides no information about the other parameters, return format, or intended use cases. An agent cannot reliably invoke this tool correctly.

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 each parameter already has a description in the schema. The tool description adds no additional meaning or connections between parameters; it only mentions 'url' implicitly. The baseline for high coverage is 3, and the description does not exceed it.

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), which is clear and not a tautology. However, the input schema lists 9 parameters (ref, city, feed, host, json, path, zone, query) that are not mentioned in the description, implying the tool does far more than just check a URL. This ambiguity undermines clarity and differentiation from siblings like browser-url-ok and 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 offers no guidance on when to use this tool versus alternatives. It does not mention any sibling tools, exclusions, or preferred contexts. An agent seeing many similar tools (e.g., browser-url-ok, normalize-url, validate-json) has no basis for choosing this one.

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