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

Beyond the annotations, the description adds meaningful behavioral context: each query consumes 0.01 USDC, sessions are limited to 20 queries, and the tool targets a specific paid listing (cvewatch). This tells the agent the operation is monetized and quota-bound, which is important for invoking it correctly. No contradiction with the annotations exists.

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 three tight sentences that cover purpose, the free alternative, listing details, price, quota, and required sequence. Every sentence contributes distinct value and the structure is easy to scan. No fluff or repetition exists.

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 definition provides essential routing context: sequence, cost, quota, and the free preview path. However, with no output schema and no mention of return values, response shape, or query syntax, an agent cannot fully anticipate the result of the call. Optional receipt-related parameters are also left unexplained, so the definition is adequate but not complete for confident invocation.

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%, so the tool description needed to compensate, but it does not explain the required query parameter format, k, delivery_receipt, or sandbox_receipt. It references 'per-query' access and the listing name but gives no guidance on how to populate the required session_id and query fields beyond what the schema already provides. The description therefore adds almost no parameter-level meaning.

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 communicates that this tool provides paid access to live data listings and places it as the final step in the data_session_open → data_session_fund → data_session_query sequence. It also distinguishes the paid path from data_preview. However, the primary verb 'Buy' describes access rather than the query execution itself, so the purpose is clear but slightly indirect.

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 sequence data_session_open → data_session_fund → data_session_query explicitly tells an agent the expected call order, and the 'first taste free via data_preview' line routes free exploration to a sibling tool. It also gives price and per-session query limits, which help determine when this paid tool is appropriate. It does not discuss exclusions or alternatives beyond data_preview, but the core guidance is solid.

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