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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world; the description adds real context beyond that — no auth required, the one-time confirmation link only exists while the cart is open, lines are re-priced from the live menu, and the order id appears only after guest confirmation.

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 dense sentence with the key and the returned state set front-loaded; every clause carries information. Slightly long and run-on, which keeps it from a 5.

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?

With no output schema, the description carries the return-value burden and does so well: it enumerates the state values and the conditional fields (confirmation link, order id). Nothing an agent needs to call or interpret this read correctly is missing.

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?

Only one parameter and the schema carries no description (0% coverage), though it does encode the format via a 32-hex pattern. The description confirms cart_id is the key but adds no format or lookup semantics beyond the schema, so the baseline 3 is appropriate.

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 ('Read an anonymous cart by cart_id') and enumerates the fields returned, so an agent can distinguish it from create_cart or get_order_status without opening a schema. The 'anonymous cart' scoping is precise.

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?

Clearly signals the operating context ('PUBLIC tool, no auth') and the keyed lookup (by cart_id), which implies when it applies. It stops short of naming an alternative or an explicit when-not condition, so it falls short of a 5.

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