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

Annotations already cover safety (readOnlyHint=true, openWorldHint=false), but the description adds two useful facts: the call is free and the output is illustrative rather than real data for a resource. It does not say whether the sample is static/fixed or rate-limited, which matters for a preview endpoint.

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?

Two short sentences with the cost signal ("Free.") front-loaded ahead of the purpose. Nothing is wasted and the key differentiator leads.

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 one-parameter preview endpoint with safety annotations and no output schema, the description covers what is needed to decide to call it. Minor gaps: whether the sample varies by input, and its approximate shape/size.

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 0% and the single `tool` parameter is undocumented in the schema, but its enum values are self-descriptive tool names matching the siblings, so minimal explanation is needed. The description only implies the parameter selects which tool to preview, adding little beyond the enum itself.

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?

States a specific verb+resource ("returns an example" of a tool's output) and frames its role relative to the paid siblings as a free preview. An agent can tell it is a preview tool, though it never names the sibling tools it previews or what the sample contains.

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?

"so you can decide before paying" gives a clear usage condition: call this before committing to a paid tool. It does not state when not to call it (e.g., once the paid tool is already chosen), so it stops short of explicit alternatives/exclusions.

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