Buy a product

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

With no annotations provided, the description carries the full burden. It explicitly warns 'Moves real money – only call this once you intend to complete the purchase,' disclosing the irreversible, financial nature. It also emphasizes the strict denomination match and price volatility. This is strong behavioral transparency for a mutation tool.

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 sentences with no filler. The core action is front-loaded, followed by critical constraints and a warning. Every sentence earns its place.

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 essential prerequisites (get_product), required conditional fields (recipient), and the irreversible nature. However, with no output schema, it does not mention what the tool returns (e.g., an order ID), which could be useful for the agent. This minor gap prevents a perfect score.

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 already describes 3 of 4 parameters (75% coverage), including the exact-match requirement for denomination and the conditional recipient. The description adds extra meaning by explaining the E.164 format for phone numbers (no leading +) and reinforcing the need to fetch current prices. This goes beyond the schema, so a 4 is appropriate given the high baseline.

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 the action: 'Places a live order, debited from your prepaid balance.' This is specific and distinguishes it from premium or SMM order tools by the emphasis on prepaid balance and denomination, even though it doesn't name siblings explicitly. The title 'Buy a product' reinforces the purpose.

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 gives a clear prerequisite: call get_product first to get current price and valid denoms. It also warns to only call when intending to complete the purchase. However, it does not explicitly state when not to use this tool versus alternatives like create_premium_order or create_smm_order, though the sibling names and the 'prepaid' context imply it.

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