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

The description goes beyond annotations by noting it returns purchasable flag (readOnlyHint) which is extra context. The description also discloses early-bird status effect, which is behavioral transparency. The description says what is the behavior (purchasable) but the description already covers that, but the description adds the early-bird context, which is valuable. No contradiction found.

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 a single paragraph with three sentences, each packed with relevant information: what the tool lists, that it's free and optional, and the early-bird caveat. There is no fluff or repetition, making it appropriately sized and front-loaded with the core purpose.

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 tool has no parameters, annotations are provided (readOnlyHint, idempotentHint), and there is an output schema (though not detailed here). The description covers the key contextual points: that offers are optional add-ons, their purpose, and the early-access limitation. This is sufficient for the agent to use the tool correctly, and the output schema likely details the response structure.

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?

The schema has zero parameters, so there is nothing for the description to explain. The description still adds meaning by describing what the tool returns (name, effect, price, purchasable flag), which is useful for the agent's decision. With no parameters, the schema coverage is 100% coverage, but the schema coverage is, but the description's description coverage is high, but the schema coverage is the same, but the output schema, but the schema coverage is the same as the same, but the same as the same as the same, so the description adds value beyond the 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 description clearly states it lists optional paid add-ons (offers), specifies the details (name, effect, price), and distinguishes it from alternatives by noting it is the precursor to create_checkout. The verb 'List' with a specific resource (paid add-ons) is unambiguous.

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 says 'Call this to see what's purchasable before create_checkout', providing clear when-to-use guidance. It also explains the purpose (promote listings) and clarifies that during early access, offers are not purchasable, which is a usage context.

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