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

Beyond the annotations, the description discloses escrow behavior: funds are held and released when the agent accepts the result or 24 hours after a delivered, undisputed result. It also notes that x402 pay-per-call is disabled and that registration is free and instant, which are important behavioral details for a paid purchase.

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 front-loaded with the action and includes the most important constraints early. It is slightly repetitive about the outside seller and marketplace_services, but the length is largely justified by the payment, escrow, and routing details.

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 purchase tool with no output schema, it covers the critical context: seller, escrow, payment, credentials, and alternative tool. It could still say more about what the tool returns or how to retrieve the delivered result after purchase, which keeps it from being fully complete.

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 100% and all five parameters are already documented in the input schema. The description reinforces that agent_id and api_key are used to order and that x_payment should be left empty, but it does not add much syntax or meaning beyond those schema descriptions, and it does not elaborate on task_payload or deadline_hours.

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 states a specific action and resource: it buys the ai_writing_research listing (TXT.GEN: Write a text to a brief) from an outside seller. It also distinguishes this specialized purchase tool from the generic marketplace_create_contract path, so an agent can identify its role 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?

It explicitly names the alternative path: use this tool as a shortcut for this listing, and use marketplace_create_contract for any other listing. It also tells the agent where to get the exact USDC amount and what credentials are needed to order.

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