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

While annotations already mark this read-only/idempotent/non-destructive, the description adds concrete behavioral facts: public metadata only, never corpus rows, optional question echoed back, and the default routed-session listing behavior. It also discloses the access context (no API key) and frames the output scope beyond what annotations alone provide.

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 dense but every clause earns its place: access signal, output fields, data boundary, routing default, parameter behavior, and buy path. The flow is front-loaded and visually structured with arrows, making the decision sequence easy to extract.

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 two-optional-parameter read-only preview tool, this is complete: it covers what is returned, what is not returned, how parameters behave, and the next step in the overall workflow. The lack of an output schema is compensated by the explicit list of returned fields.

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 100%, yet the description still adds value by explaining the routed-session default for slug and the echo behavior for question. It reinforces the 300-character limit and optionality, so the agent can use the parameters correctly without relying on schema parsing alone.

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 exactly what the tool does: preview a paid data listing with title, price, up to 3 sample questions, and a summary excerpt. Explicitly distinguishes it from downstream paid querying by naming data_session_query as the buy path, so an agent can tell this free preview apart from sibling data tools.

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 description explicitly says to call this now when a free taste is needed and no API key is available, then lays out the exact sequence for the paid path: register → data_session_fund → data_session_query (sandbox_receipt=true). It also explains the routed-session default, so the agent knows when to pass slug versus rely on the session.

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