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

The paid nature is disclosed with concrete pricing and session limits: 0.01 USDC per query and max 20 queries/session. This adds meaningful behavior beyond the annotations, which only say the operation is non-read-only and non-idempotent. It does not describe failure or delivery-receipt behavior, but the commercial/quota model is transparent.

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: three sentences covering the paid nature, the specific listing and price, and the required session sequence. It is slightly dense but every sentence contributes useful operational context. The structure could be improved by leading with what the tool does rather than the commercial framing.

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?

There is no output schema and low parameter coverage, so the description must carry more of the invocation context. It omits the expected return shape, query language or format, and what happens on insufficient balance or invalid receipts. The session flow and pricing are covered, but an agent would still need more details to invoke this correctly.

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 only 40%, and the description does not compensate for the undocumented parameters. query syntax, k semantics, delivery_receipt, and sandbox_receipt are left unexplained. The session_id purpose is already covered by the schema, so the description adds little parameter-level value.

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 says the tool buys per-query access to live data listings and the schema description clarifies it runs a prepaid query against a funded data session. The sequence data_session_open → data_session_fund → data_session_query positions it as the final query step. It is less direct than saying 'execute a query' and mixes in listing-specific pricing, but an agent can still identify the operation.

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 an explicit prerequisite chain: data_session_open → data_session_fund → data_session_query, and points to data_preview as the free first taste. This tells the agent when in the session lifecycle to call this tool. It does not spell out failure conditions like an unfunded session, but the sequencing guidance is clear enough.

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