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

Annotations declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that: it discloses the content the tool returns (sizes/prices with candles and card, flavors, earliest day, exclusions, photos, design questions) and the crucial behavioral fact that ordering is a separate step via check_order. A minor gap: it doesn't explicitly say the output is informational rather than action-taking, but the combination of annotations and content list makes it clear.

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 first sentence is a long comma-separated list that is somewhat dense and front-loaded with the resource but not the core action. It could be tightened; however, every item in the list corresponds to distinct content the tool provides, so most of it earns its place. The second sentence is an effective redirect sentence.

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 an output schema present, the description needn't explain return values, and it doesn't (though it does list content categories). Annotations cover safety. The agent knows what the tool provides, that ordering goes elsewhere, and that 'guests' is optional. One small gap: it doesn't state whether the tool is a static reference or dynamically personalized by the guests parameter, but that's a minor omission given full schema coverage and a simple read-only tool.

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 the single optional 'guests' parameter is fully documented in the schema. The description does not mention 'guests' directly but says sizes are covered and '(with candles and a card)'. Baseline 3 for full schema coverage; slight uplift because the description lists that sizes/prices are returned, which helps the agent know why guests matters. Still doesn't add syntax beyond the schema.

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 the resource (custom decorated cakes) and enumerates what it covers: sizes, prices, flavors, lead time, exclusions, photos, design questions. It's clearly a reference/consultation tool, not an ordering tool. However, the core action verb is vague ('options' serves as a noun list) and the title 'Design a custom cake' is somewhat misleading since the actual ordering is routed to check_order.

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?

Explicitly says 'A cake is ordered through check_order with its cake details,' which is strong routing to the sibling. It also implies when to use (any occasion, to explore options) but does not state when NOT to use it (e.g., for non-cake items) or which sibling handles general menu queries.

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