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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuine auth context ('No API key needed') and a rate limit (max 20 queries/session), which is useful. However it also states a price (0.01 USDC/query) alongside 'FREE ... no payment', an internal inconsistency that muddies rather than clarifies behavior.

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 free/no-key/payment claim is repeated three times ('No API key needed', 'FREE preview — no key, no payment', 'Try one of the sample questions now'), and the pricing line contradicts that claim. It is bloated with promotional filler instead of front-loading a crisp statement of what the tool returns.

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 two-param, optional-argument, read-only preview with no output schema, the description covers auth and quota, which are the main behavioral unknowns. But it omits what a preview actually returns (the schema only says 'public metadata only') and never positions the tool against its paid sibling, leaving real gaps.

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%, with both slug and question fully documented in the schema, so the baseline is 3. The description's sample questions loosely illustrate the question parameter but add no syntax, format, or constraints beyond the schema.

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 a listing and repeatedly claims 'FREE preview', so an agent can infer this returns a free sample of a data listing. But it never states a clean verb+resource ('preview a data listing without payment') and is dominated by sales copy rather than a purpose statement. It only weakly distinguishes itself from the paid sibling data_session_query.

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 text urges 'call this now' and 'Try one of the sample questions now', which is a nudge rather than guidance. It never says when to prefer this over data_session_query or the session tools, nor what the preview does not cover. No when-to-use/when-not logic is present.

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