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

Annotations already declare this a non-read-only, non-destructive, non-idempotent mutation. The description adds genuinely useful behavioral detail beyond that: the exact prices (19.00 for 7 days, 49.00 for 30 days) and that billing is in the listing currency. It stops short of warning that repeat calls incur repeat charges or describing payment failure behavior.

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?

One compact sentence that front-loads the purpose and folds pricing into a parenthetical. No wasted words, though the clipped 'Seller:' prefix and missing verb make it slightly less readable than it could be.

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 simple 2-parameter purchase tool with full schema coverage and annotations, the description covers the essentials: what it does and what it costs. It is incomplete for a paid mutation in that it never states that funds are charged, what happens on insufficient balance, or whether the boost applies immediately.

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%, so the baseline is 3, but the description adds value the schema does not: it maps each enum duration to a specific price, which helps the agent and user choose between '7' and '30'. The required listing_id is fully explained in 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?

States the concrete outcome—sponsored placement at the top of search—and the two purchasable durations, so an agent knows this buys promotion for a listing. It lacks an explicit action verb ('boost') and does not contrast with adjacent tools like update_listing, but the resource and effect are unmistakable.

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 'Seller:' prefix implies the audience and use case (promote one's own listing), and prices make the paid nature clear. However, there is no explicit when-to-use guidance versus alternatives, no mention that the listing must presumably be live, and no prerequisites such as account balance.

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