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

With no annotations, the description carries the full burden. It usefully discloses that the fetch targets a public resource and returns counts only, but it never explains the unrelated-looking params (json 'discarded after the check', zone 'IANA timezone name') or any failure/latency behavior, leaving the tool's actual footprint opaque.

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 front-loaded sentence states the action, scope, and output limitation with zero filler. Every word earns its place.

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 an unannotated tool with four optional params and no output schema, one short sentence is insufficient. The description leaves unresolved which params trigger robots.txt fetching, what 'group counts' look like in the response, and why json/zone parameters exist, so the agent must guess.

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% (baseline 3), the description adds no param-level meaning and actually creates ambiguity: 'Fetch a public robots.txt' does not say whether url or host is the target, while the schema describes url as 'normalize or cite' and json/zone as validation/timezone inputs unrelated to robots.txt. An agent cannot reliably map the described behavior to the right parameter.

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 ('Fetch'), a concrete resource ('public robots.txt'), and a precise output scope ('group counts only'), so an agent knows exactly what the tool does. It does not explicitly contrast itself with the sibling 'citation', so it stops short of a full 5.

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 the sibling 'citation', and no exclusions are stated. The context 'when you need robots.txt group counts' is only implicit, and the description gives no hint about which of the four optional params is relevant.

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