Add Cart Items

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

Annotations already indicate it's a write operation (readOnlyHint=false) with possible destructive effects (destructiveHint=true) and non-idempotent behavior (openWorldHint=true). The description adds minimal additional context—'deltas' and 'active cart'—but does not disclose side effects like item creation or accumulation.

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 concise sentence (12 words) with no filler. It is front-loaded with the action and object, making it efficient for agent scanning.

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 no output schema and one nested parameter, the description is brief. It lacks details on behavior for new items (creation vs. update) and the meaning of 'deltas' in relation to the positive-only schema constraint. The context is adequate but not fully comprehensive.

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 0%, so the description must carry the burden. It clarifies that productId is a 'Voila product UUID' and quantity is a 'delta' (change rather than absolute), which adds value beyond the raw schema. However, it does not explain the meaning of a delta (e.g., positive only) or the structure of the items array.

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 action ('Add'), the object ('product quantity deltas'), and context ('active cart using Voila product UUIDs'). It effectively distinguishes from sibling tools like voila_get_cart (read-only) and voila_remove_cart_items (removal) by specifying 'deltas'.

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 implies usage for modifying cart item quantities, but does not explicitly state when to choose this over voila_remove_cart_items or how to handle new items. It also does not clarify that quantity must be positive (deltas are strictly additive according to schema) or mention prerequisites like an active session.

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