Read back one of YOUR carts by id: line items and estimated totals. Owner-scoped, so another agent's id returns not_found. REQUIRES IDENTITY on a signature-required Terminal.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | The cart id. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses owner-scoping, not_found behavior for foreign ids, and the identity requirement, which are key behavioral traits. It does not cover all edge cases (e.g., missing identity) but is transparent for a simple read operation.
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 two sentences, with the core purpose front-loaded. No redundant phrasing; every clause adds value (scope, return contents, error behavior, prerequisite).
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?
Given one parameter and no output schema, the description covers the input semantics, output contents (line items and estimated totals), error case (not_found), and required identity context. This is sufficient for an agent to correctly invoke the 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?
The schema only says 'The cart id', but the description adds that it must be YOUR cart id and that using another agent's id yields not_found. This significantly enriches the parameter's meaning, so it goes beyond the schema baseline.
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 explicitly states 'Read back one of YOUR carts by id' with a specific verb and resource, and mentions the return content (line items and estimated totals). It distinguishes from siblings by noting owner-scoping and not_found behavior.
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: it's for reading your own cart, and explicitly warns that another agent's id returns not_found, which effectively excludes that use case. It also states the identity requirement on a signature-required Terminal, giving a prerequisite. No explicit alternative tool is named, but the guidance is clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Most tools map to a distinct lifecycle step, and the detailed descriptions separate discovery, cart, checkout, payment, order, and wishlist concerns well. However, get_product and lookup_catalog are largely the same lookup by identifier, discover_products and search_catalog overlap across scope, and update_checkout is actually a read-only no-op.
The set overwhelmingly follows a verb_noun pattern: create_cart, get_checkout, cancel_checkout, complete_checkout, search_catalog. Minor deviations are the wishlist_* resource-first subgroup and the misleading update_checkout, which does not perform an update.
At 23 tools, this sits at the heavy end of the range, though the broad commerce lifecycle does justify substantial surface area. The count is inflated by redundant product lookup tools and a no-op update_checkout, so a more trimmed set in the low-to-mid teens would be healthier.
The server covers the full shopper lifecycle well: discovery, product lookup, cart, checkout, payment, order placement, order read, refunds, and wishlist. Gaps are minor and workable, such as update_checkout not actually supporting updates and no explicit order-cancellation path once a checkout is complete.
