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

Beyond the annotations (idempotent, non-destructive, non-read-only), the description adds that this is a paid per-query purchase, includes a concrete rate (0.01 USDC/query), and discloses that funding is platform-executed before querying. This clarifies the side-effect of spending funds and does not contradict any annotation.

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?

Three short sentences with the main purpose front-loaded; the listing example and price are concrete but specific to a sandbox offering. Each sentence still adds useful operational context, so the description is appropriately sized.

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 tool with idempotent and safety annotations, the description provides enough context: what is bought, how funding is executed, and what it enables. It does not describe return values, but with no output schema and only session_id input, that is a minor 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?

The schema already describes session_id as the UUID of a data session opened via data_session_open, and schema coverage is 100%, so the baseline applies. The description adds no new meaning about the parameter 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?

The description opens with a specific action and object: 'Buy per-query access to live data listings,' and clarifies the downstream relationship with data_session_query. It does not explicitly name or contrast the similar sibling data_session_funding_package, so it stops short of full sibling differentiation.

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 a clear workflow — preview free via data_preview, fund, then data_session_query — and notes that funding is platform-executed. However, it gives no explicit guidance on when to use this tool versus data_session_funding_package or data_session_attach_escrow, leaving the choice largely to inference.

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