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

The description explains the surprisingly non-read-only annotation (readOnlyHint=false): the tool writes into the shop's own cart and empties it afterwards, so a mutation is expected yet nothing is bought. It further discloses that no personal data is involved, what is deliberately left unknown (tax and fees at checkout, delivery date unless the cart names it), and the degraded path for unsupported platforms. This adds real behavior beyond the annotation block.

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 no-order guarantee and single-cart/single-ZIP scope are front-loaded, and the following sentences cover returns, unsupported platforms, and sequencing without repetition. The prose is dense with em-dashes and parentheticals, which costs some scannability, but no sentence 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 seven-parameter tool with no output schema, the description states what the answer contains (items, delivery options with prices, subtotal) and what is explicitly not returned. Combined with the cart-emptying side effect and the fallback behavior, an agent has everything needed to call it correctly and to interpret the result honestly.

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 100%, so every parameter including deliver_to, delivery_date, options and items is already documented in structured form. The description reinforces the delivery_date semantics ('asks for a day') but supplies no syntax, defaults or constraints that the schema does not already carry, so the baseline of 3 applies.

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 opens with a specific verb and resource: 'Prices ONE cart in the shop's own public cart (Shopify or WooCommerce) to ONE ZIP.' It also states the key scope constraint that 'orders nothing' and that the cart is emptied afterwards, which separates it cleanly from place_order and check_availability without the agent needing to open any schema.

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 sets clear conditions: use it to learn what an order would cost before committing, and it warns that other platforms return 'quote not available' with the reason and order link. It also invokes the sequencing rule that reading, quoting, requesting and ordering stay separate. It stops short of explicitly naming a sibling as the alternative when a full order is actually wanted, so it is clear context rather than complete routing.

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