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

Annotations already cover readOnlyHint=false, destructiveHint=false, and idempotentHint=true. The description adds that funding is 'platform-executed' and that access is per-query, which is useful, but it does not disclose side effects such as balance deduction or session state changes beyond what annotations imply.

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 compact and front-loaded with the core purpose. The specific listing and price add context but are somewhat tangential to the tool's general behavior; still, there is no wasted wording.

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 a fully documented schema and safety annotations, the description covers the main workflow: preview, fund, query. It does not explain return values or how this relates to data_session_funding_package, but those are not essential for a correct call.

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%, and the single session_id parameter is already documented as a UUID from data_session_open. The description adds no parameter-specific meaning, so the baseline of 3 applies.

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 states a clear action ('Buy per-query access') and a specific resource ('live data listings'), and names a concrete listing. It distinguishes itself from data_preview by noting the free first taste, but does not explicitly differentiate from data_session_funding_package or data_session_attach_escrow.

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 provides clear usage context: preview first via data_preview, then fund, then query via data_session_query. It implies the ordering but does not explicitly state when not to use this tool or name alternative funding-related siblings.

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