buy_now

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

With no annotations, the description fully discloses all behavioral traits: commits real money on production, safety gate with confirm_amount, eBay's rejection for quantity limits, and optional max_bid_override to bypass the safety cap. Returns and exceptions are detailed.

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 well-structured with clear sections (summary, implementation note, warning, parameters, returns). It is front-loaded with the core purpose. However, it is somewhat lengthy; the parameter descriptions could be slightly condensed, but still efficient.

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?

Given the complexity (6 params, production warnings, safety gates) and lack of annotations, the description is extremely complete. It covers purpose, usage, behavior, parameters, return values, and exceptions. No output schema exists, but return values are described.

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%, but the description adds detailed semantics for each of 6 parameters: item_id source, confirm_amount must equal BIN price, quantity default and limit warning, currency default, max_bid_override purpose, and host default. This fully compensates for the lack of schema descriptions.

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 'Purchase a Buy It Now listing immediately at the listed price,' using a specific verb and resource. It contrasts with sibling tools like place_bid (for auctions) and make_best_offer.

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 warns about production host committing real money, advises inspecting server_info() before calling, and recommends looking up the current price with get_item() to prevent errors. It also notes multi-quantity limits.

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