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

With no annotations, the description carries the burden of disclosing behavior. It does say the fetch targets public robots.txt and that only group counts are returned, indicating a read-only, aggregate operation. However, it does not mention error behavior, timeouts, redirects, or that many supplied parameters are discarded after validation.

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, front-loaded sentence with no filler; 'group counts only' adds meaningful output scope. It earns its place, but it is slightly too terse given the complexity of the input schema.

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?

A 9-parameter schema with no required fields, no annotations, and no output schema demands far more context than this. The agent cannot determine which parameter to use, what the returned group counts look like, or how failures are surfaced. The description is not sufficient to invoke the tool reliably.

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?

Although schema coverage is 100%, the parameter descriptions are generic and not tied to robots.txt. The description never explains whether the agent should supply 'url' or 'host' to select the target, and several parameters ('city', 'feed', 'json', etc.) are clearly irrelevant yet still present. This makes correct invocation ambiguous.

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 names a specific verb and resource ('Fetch a public robots.txt') and states the exact result ('return group counts only'). This clearly distinguishes it from broader fetch/status tools like web-fetch and fetch-status, which would return more content or status information.

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 about when to use this tool versus siblings such as web-fetch, fetch-status, or normalize-url. The only usage signal is the implicit connection between the tool name and robots.txt, so the agent must infer when this tool is the right choice.

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