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

With no annotations, the description carries full behavioral disclosure. It reveals important behaviors: creating a new cart when cartId is absent, treating cartId as an access token, recomputing prices from the live menu on every read (never stored), including a checkoutUrl, and supporting add/change/remove operations. It does not mention permissions, reversibility, or error handling, but it provides substantial insight beyond the schema.

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 a single three-sentence paragraph that front-loads the main purpose and then provides necessary operational details. Each sentence adds unique value: creation semantics, update formats, and price/checkout behavior. It is somewhat dense but not bloated, appropriately sized for the tool's complexity.

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?

Despite having no output schema and only 25% schema description coverage, the description covers the essential invocation logic: how to add/change/remove lines, when to include cartId, what to do with the returned cartId, and how to place the order via create_order. It also mentions the checkoutUrl in the response. Missing are details about the full return structure, error cases, and authorization requirements, but for the described use case it is largely complete.

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 description coverage is only 25% (only cartId has a description), so the description compensates by explaining the complex 'updates' parameter in detail: the exact shapes for adding, changing, and removing lines, and the meaning of cartId as an access token. It does not elaborate on 'domain' and 'language', leaving those ambiguously documented, but the critical parameter semantics are well covered.

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 tool's function: 'Build the guest order step by step in a server-side cart,' using a specific verb ('build') and resource ('cart'). It distinguishes itself from siblings by explicitly noting that the cart 'can be placed as an order with create_order(cartId)' and implying reading via get_cart. The scope (server-side cart, guest order) 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?

The description provides clear context for when to use the tool: to build a guest order step by step, and it names an alternative, create_order, for placing the cart as an order. It also explains the conditions for creating a new cart (omitting cartId) versus updating an existing one. However, it does not explicitly state when not to use this tool or mention alternatives like get_cart for reading.

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