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

The description adds useful behavioral context beyond the annotations: a cost of 0.01 USDC per query, a max of 20 queries per session, and a paid/consumptive model. This signals side effects such as deducted balance or rate limiting. It does not mention failure behavior for unfunded sessions, but the schema and sequence partially cover that.

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-structured: each sentence earns its place. It front-loads the core purpose, then states price/limits, then gives the workflow sequence. No redundant filler or repeated schema information.

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 basic call, the description plus schema provides enough context: session_id and query are required, the sequence explains prerequisites, and the cost/limit is stated. However, with no output schema, return behavior is undefined, and optional parameters delivery_receipt and k remain unexplained, leaving gaps for non-basic usage.

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 narrative description does not compensate. The meaning of k, delivery_receipt, and the query string format is not explained; session_id is only implied by the sequence and already described in the schema. Optional parameters remain underspecified, making this the weakest dimension.

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 tool as paid per-query access to live data listings and places it as the final step in a session workflow. It distinguishes itself from data_preview and from data_session_open/data_session_fund via the explicit sequence. The phrase 'Buy per-query access' is slightly indirect, but the tool name, title, and schema description make the action clear.

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 names data_preview as a free alternative and provides the prerequisite sequence data_session_open → data_session_fund → data_session_query, so an agent knows when in the workflow to call it. It could more explicitly state 'do not use before funding' or 'use data_preview for free access,' but the guidance is strong enough.

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