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

Annotations already declare readOnly/idempotent/non-destructive, so the description focuses on what they can't say: the agent_checkout field is informational only and does NOT place an order, which prevents a costly misinterpretation. It also advises retaining id, token, and continue_url, though it doesn't describe error behavior for an invalid or expired token.

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 tight sentences, front-loaded with the action, followed by retention guidance and the critical agent_checkout caveat. No filler, though the third sentence is long enough to be split.

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 usefully names the key return fields (full cart id, owner token, continue_url, agent_checkout) and their purpose. Missing only edge-case behavior such as what happens with an invalid token or a cancelled cart.

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 67% and the schema itself already says cart_access_token is 'returned by create_cart', so the description largely restates the same provenance. The nested 'meta' parameter remains undocumented in both places.

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 (Retrieve) and resource (Shopify-owned cart), and explicitly ties it to the create_cart flow, distinguishing it from create_cart/update_cart/cancel_cart siblings. An agent can identify the operation without opening the schema.

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?

It establishes the precondition clearly: the cart must have a cart_access_token produced by create_cart. It doesn't spell out when a caller should prefer get_cart vs get_checkout or update_cart, so it stops short of full alternative routing.

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