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

Annotations only supply destructiveHint=true; the description adds real behavioral context beyond that — billing starts, the rental clock starts, and EZRentOut may email the customer per account settings. It does not cover prerequisites (what order state is required) or error behavior, keeping it below a 5.

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 short sentences, front-loaded with the outcome and side effects, then the parameter rule, then the endpoint. Every sentence carries information an agent needs; nothing is padded.

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 destructive, billing-triggering mutation with no output schema, the description covers effects, email side effect, and the key either/or parameter rule. It stops short of saying what the call returns (e.g., updated order) or whether the action can be undone via return_order, which an agent would want.

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 baseline is 3, but the description adds a genuine cross-parameter rule the schema cannot express: supply rentout_date and return_date, or use use_current_datetime. It also ties the call to the order number in the endpoint path.

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 a specific verb and resource ("Check an order out") and immediately defines the effect: assets go to the customer, rental clock and billing start. This clearly separates it from siblings like book_order, return_order, or create_order without needing schema inspection.

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?

Implies the right context (an existing order being handed to a customer) and gives conditional parameter guidance ("Give rentout_date and return_date, or use_current_datetime"), but never names a sibling alternative or exclusion such as return_order for reversal or book_order for reservations.

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