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

The annotations are all false and provide little safety or behavioral context, so the description carries the burden. It usefully discloses the per-query cost, the 20-query session limit, and the prerequisite sequence. However, it does not disclose what happens to the session balance, what a successful query returns, or how the delivery_receipt and sandbox_receipt parameters change the behavior.

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 well-ordered, leading with the core purpose and then giving the specific listing, pricing, and sequence. It has no filler, though the specific listing and pricing details could become stale or arguably belong in a data catalogue rather than the tool definition. Still, every sentence earns its place for a paid data access workflow.

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?

The essential invocation context is present: the open -> fund -> query pipeline, the specific dataset, the price, and the per-session limit. However, with no output schema and three optional parameters left unexplained, an agent may not know what to pass for k or delivery_receipt, nor what the tool returns on success or failure. It is adequate for the simple happy path but incomplete for robust autonomous use.

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%, covering session_id and sandbox_receipt, while query, k, and delivery_receipt are undocumented in the schema. The description names no parameters and does not explain what query should contain, what k controls, or what delivery_receipt is for. Since coverage is low, the description was expected to compensate but does not.

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 identifies the action as buying and running per-query access to live data listings, and the sequence line establishes this tool as the final query step after opening and funding a session. It distinguishes itself from data_preview by framing that as the free alternative. The purpose is clear, though the phrasing 'Buy per-query access' is slightly more commercial than a direct 'query the session' statement.

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 states the required sequence: data_session_open -> data_session_fund -> data_session_query. It also names data_preview as the free alternative for a first taste, which tells an agent when not to use this paid tool. This is strong, actionable usage guidance.

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