Add to cart

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

Annotations already disclose this is a non-readonly, non-idempotent, non-destructive mutation, so the description's added value is the same-store constraint, which is genuine behavioral information not present in schema or annotations. It does not explain the non-idempotent behavior that matters most here – whether adding the same item twice increments quantity or creates a duplicate line – nor any auth or stock/availability failure modes.

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 short, front-loaded sentences with no filler; the action is stated first, then the constraint, then the conditional options rule. Slightly clipped to the point of omitting needed context, but nothing is wasted.

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 6-parameter mutation with annotations covering the safety profile and no output schema, the description covers the essential constraint and the options prerequisite. The remaining gaps – non-idempotent duplicate behavior and the mart/bites module choice – are meaningful but secondary, so it is close to complete rather than fully 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 coverage is 67%, and the schema already documents module, options, variant and session_key. The description adds only a pointer to foran_product_details for discovering valid option values, while module selection (mart vs bites) and quantity semantics go unexplained beyond the schema's own text. Baseline 3 is appropriate given the moderate coverage.

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?

Names a specific verb and resource ('Add a product to the customer's cart'), which is unambiguous against most siblings such as foran_cart_remove, foran_cart_update and foran_place_order. It does not explicitly say how it differs from foran_cart_update (which presumably changes quantity/existing lines), so it falls short of full sibling differentiation.

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 a useful precondition (all items in one order must come from the same store) and routes the agent to foran_product_details when the product has options. It never states when NOT to use it (e.g. to change quantity on an existing line, use foran_cart_update) and does not mention that a logged-in session_key is required, leaving real usage decisions implied.

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