list_services

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds valuable context about the temporary unavailability of card checkout for instant products, and states that request-based services remain operational. It also discloses the return structure. This goes beyond what the empty schema provides, though it does not mention rate limits or authorization.

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 information-dense and front-loaded with the main purpose. The lists of services are detailed but necessary for clarity. The note about payment processor unavailability is important but could be considered an addendum. Overall, it is structured effectively and every sentence serves a purpose, though it is slightly verbose.

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 there is no output schema and no annotations, the description is remarkably complete. It specifies the tool's purpose, the categories of services, the return value's structure, and a temporary operational caveat. For a zero-parameter list tool, this provides sufficient context for an agent to select and invoke it appropriately.

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?

There are zero parameters, so the baseline is 4. The description adds meaning by enumerating the product types and explaining that the returned product_type/variant ids are required for order_service. Since there is no schema to describe parameters, the description is the sole source of semantic information, and it does that well.

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 uses a specific verb ('List') and resource ('transactable services + EUR prices'), and further clarifies the audience (buyers vs agents) and the exact output (product_type, variant ids, price). It clearly distinguishes this from sibling tools like order_service and request_service by stating that the returned data is what order_service needs.

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 provides context for when to use the tool: it lists the services and prices, and explicitly states that the output is needed for order_service. It also notes that request-based services and buyer enquiries work regardless of payment processor issues, implying a use case for request_service. However, it does not explicitly say 'use this when you need prices' or provide exclusions relative to other list/search tools.

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