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

With no annotations, the description must disclose behavioral traits, but it only says 'Fetch a public robots.txt' without mentioning that most schema parameters are discarded after checks, that the tool performs no disk access, or that it may make network requests. Agents have no idea that passing 'city' or 'json' will have no effect on output.

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 sentence, which is concise, but it is under-specified. It front-loads the purpose but omits essential mapping to parameters and usage context. The brevity is not an asset because it fails to earn its place by providing meaningful guidance.

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 nine optional parameters, no output schema, and no annotations, yet the description only mentions robots.txt. It doesn't explain how to select the correct parameter, what 'group counts' means, or whether other parameters are accepted but ignored. This is completely inadequate for an agent to invoke the 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 description coverage is 100%, so each parameter is individually documented (e.g., 'Git ref name; discarded after the shape check'). The tool description adds no extra meaning beyond the schema, and it doesn't clarify which parameter is the robots.txt URL. Thus baseline 3 is appropriate given high schema 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 verb ('fetch') and resource ('public robots.txt') with a clear output ('group counts only'). However, it fails to explain how the input schema relates to this purpose; none of the nine parameters is explicitly designated as the robots.txt URL, and several parameters (city, feed, json, path, zone, query) seem unrelated. This ambiguity prevents the agent from knowing what to pass.

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 provides no guidance on when to use this tool versus its siblings (e.g., fetch-status, web-fetch, domain-shape). It also doesn't mention whether this tool is intended for robots.txt only or for general shape-checking, leaving the agent without criteria for selection.

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