cart_add_simple

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

Annotations already declare openWorldHint, idempotentHint, and non-destructive writes; the description adds useful state context (cart must be empty, single shot, no payment side effect). It does not disclose what happens on a non-empty cart (error vs merge), nor how idempotency_key affects retries, which is the main behavioral unknown for a mutating tool.

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?

Two tight sentences, front-loaded with the action and followed by constraints; nothing is padded. Minor ambiguity in 'once' and the vague 'official App configuration' phrase 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?

For a mutating tool with a deeply nested 0%-documented schema and no output schema, the description is too thin: it omits how the request/checkout block is used, retry semantics tied to idempotency_key, and failure behavior on a non-empty cart. It also conflicts with the schema, which exposes ComboSelection while the text says combos need the official App.

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 0% across a nested input with request (account, store_code, pickup_at, max_amount_cny, eat_type), items, and idempotency_key, yet the description explains none of them. 'Simple uncustomized menu items' hints at items semantics but nothing covers the checkout/request block or idempotency_key.

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 concrete verb and resource ('Add simple uncustomized menu items') plus the target state ('an empty cart'), which separates it from cart_add_configured and from order/checkout tools. It never names the sibling that handles the non-simple case, leaving the agent to infer that cart_add_configured exists for that.

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?

Gives clear preconditions ('empty cart', 'once') and explicit exclusions ('No order/payment', complex combos need the official App). It stops short of routing to a sibling tool for the excluded cases, so the alternative is named only as an out-of-band app rather than cart_add_configured.

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