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

Annotations already cover read-only, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description adds genuinely non-structured context: no API key required, free preview vs the 0.01 USDC/query paid path, and a session rate limit of max 20 queries. The price statement sits awkwardly beside 'no key, no payment' and is mildly confusing.

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 text repeats itself ('No API key needed — call this now' then 'FREE preview — no key, no payment') and pads with promotional phrasing and an emoji. It is not front-loaded with the core action; the listing identity and cost caveats are interleaved with sales copy.

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 simple, annotation-rich, parameterless read tool with no output schema, the description is adequate: it conveys free guest access and an example listing. It does not clarify what the preview actually returns or how it relates to the session-flow siblings, leaving a modest gap.

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 baseline 3 applies. The sample questions illustrate the 'question' parameter's intent, but the description adds no syntax, defaults, or routing detail beyond what slug/question already document.

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 identifies the resource (a free preview of a data listing, specifically the 'awswhatsnew' AWS announcements listing) and implies scope (public metadata only, free tastes). It is identifiable against siblings like data_session_query, though the marketing framing buries the verb 'preview' rather than stating it plainly.

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?

It implies usage ('call this now', 'Try one of the sample questions now') and signals this is free versus the paid query path, but never explicitly names data_session_query as the alternative or states the condition for choosing the paid route.

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