ht_add_to_cart

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the safety profile is known. The description still earns credit by disclosing the additive (non-replacing) quantity semantics, the exact reversal path, and that nothing is ordered or charged — the latter being the key reassurance for a mutation tool on a retail account.

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 sentences, front-loaded with the action and identifier, then the accumulation rule, then reversibility. No filler and no repetition of the title.

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 single-parameter write tool with no output schema and annotations that already cover the destructive/read-only profile, the description covers the essentials an agent needs before calling: identifier, additive behavior, and undo path. It would be complete if it mentioned the out-of-stock substitution default or what state the cart is left in.

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?

Reported schema coverage is 0%, so the description should carry more weight than it does. It does pin UPC as the identifying key and clarifies that quantity is incremental rather than absolute, but it says nothing about the substitutionPolicy enum (out-of-stock behavior) or the per-call item limit.

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 gives a concrete verb plus resource plus key identifier: add groceries to the Harris Teeter cart by UPC. That is specific enough that an agent can distinguish it from cart-mutation siblings, though it never explicitly contrasts itself with ht_add_to_shopping_list, which is the nearest source of confusion.

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 useful context — items accumulate onto existing quantities, and the effect can be undone via ht_update_cart_item or ht_remove_from_cart — which implies when to reach for it. It stops short of stating when NOT to use it, e.g. that it targets the live order cart rather than a saved shopping list.

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