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

The description discloses important behavioral traits beyond annotations: it is a paid operation ('0.01 USDC/query'), it executes funding, and it enables subsequent querying. Annotations provide idempotentHint and destructiveHint but do not convey the financial/cost dimension, which the description handles well.

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-loads the core purpose. The mention of the specific listing and price is useful context, and the phrase 'first taste free via data_preview' economically communicates an alternative. A slight marketing tone is present, but it does not waste words.

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 single-parameter tool with full schema coverage and clear annotations, the description provides enough context: what the tool does, what it costs, the specific listing, and how it fits into the preview-to-query workflow. It does not describe return values or confirmation behavior, but no output schema exists to anchor that expectation.

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% and the session_id parameter is already clearly documented as 'UUID of a data session you opened (from data_session_open).' The description does not add parameter-level detail, but this is acceptable since the schema fully covers the only parameter.

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 clearly states the tool's function: 'Buy per-query access to live data listings' and explicitly says it 'Platform-executes funding so you can data_session_query.' It also distinguishes itself from the free data_preview path. However, it does not explicitly say 'fund the data session' beyond the title, relying somewhat on the tool name.

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 gives useful workflow guidance: use data_preview for a free first taste, then this tool to fund paid per-query access, then data_session_query to actually query. It does not, however, enumerate conditions for when not to use it or compare it with other funding-related siblings like data_session_attach_escrow.

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