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

Annotations already mark this as non-read-only and idempotent, but the description adds meaningful behavioral detail: save the returned orderId and statusToken, retry the same quote after a timeout, and never create another payment while an order is processing. It also clarifies that payment metadata comes from the wallet integration, so no separate payment parameter is needed.

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?

Three dense sentences front-load the action, then cover prerequisites, then provide operational guidance on response handling and retry behavior. Every sentence earns its place, and there is no filler or repetition of the schema.

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 description covers the action, prerequisites, protocol choices, returned values (orderId/statusToken), and retry policy, which is substantial given there is no output schema. It leaves the prerequisite quote flow implicit rather than referencing quote_sponsorship, but the core information needed to call and use the tool is present.

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 0%, so the description must carry parameter meaning. It maps protocol to MPP/x402, acceptedTermsVersion to 'exact current terms acceptance', and authorizedToPromote to 'authority to promote the URL'. However, quoteId and quoteToken are only implied through 'quoted' and 'same quote', not explicitly explained, so compensation is partial.

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 opens with a specific action verb and clear object ('Buy the quoted sponsored placement') and identifies the payment protocols ('via MPP or x402'). This clearly distinguishes the tool from siblings like quote_sponsorship (which creates a quote) and get_sponsorship_status (which checks status).

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 makes it clear that this is the purchasing step for an existing quote and that it requires current terms acceptance and authority to promote the URL. It does not explicitly name sibling tools or state when not to use it, but the context is clear enough for an agent to route correctly.

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