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

With no annotations, the description must disclose behavior, but it only mentions the output type. It doesn't explain that most parameters are discarded, that only public URLs are accepted, or that network access occurs. The schema hints at discarding, but the description itself provides no such context.

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 sentence with no filler, front-loading the core function. It is maximally concise, though at the expense of completeness.

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 output schema, and no annotations, the description is severely inadequate. It omits parameter usage, error behavior, and the fact that most parameters are irrelevant, making correct invocation nearly impossible.

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 descriptions are vague ('HTTPS URL to normalize or cite') and don't connect to the robots.txt purpose. The description doesn't specify which parameter is the target URL, so an agent cannot correctly map the 9 parameters to the task.

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 (fetch public robots.txt) and output (group counts only), clearly distinguishing it from siblings like fetch-status or web-fetch. It's unambiguous about the tool's primary function.

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 alternatives. There's no mention of conditions, exclusions, or comparison to sibling tools, leaving the agent to guess based on name alone.

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