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

Beyond the readOnlyHint annotation, the description discloses important behavior: unpaid calls return a 402 with price and preview count, records are priced per record with a minimum per pull, and low-quality rows are quarantined. This gives the agent a realistic model of what happens when the tool is invoked.

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 dense but every sentence earns its place: dataset qualification, de-identification, filters, pricing, payment, error behavior, and where to find the schema. It is front-loaded with the most important qualification criteria.

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 complex 11-parameter tool with no output schema, the description covers inclusion/exclusion rules, de-identification, filtering, payment, the 402 response, and a link to the sample and schema. An agent has enough context to call the tool correctly and understand the outcome.

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 coverage is only 36%, but the description compensates by grouping the filter parameters ('state, since, until, door, vendor; limit and offset') and naming the payment methods that map to buyer_key, payment, credential, and mandate. It does not explain every parameter in detail, but it adds meaning beyond the bare schema.

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 title and description state a specific verb ('Buy') and a specific resource ('provenance-qualified, de-identified demand records'), and the description clearly distinguishes this from sibling tools by emphasizing paid, qualified, de-identified data. An agent can tell this is the market-data purchase tool without opening the schema.

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 clear context for when to use the tool: it is the paid source for qualified, de-identified demand records, with explicit filters and payment requirements. It does not explicitly name sibling tools or state when not to use it, so it stops short of the top tier.

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