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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces this with 'Nothing is reserved or ordered.' It also discloses behavioral detail annotations cannot carry: sale and quantity-break pricing rules, CAD currency, and conditional delivery-estimate computation. Missing only failure modes (bad coupon, invalid postal code, unavailable variant).

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 sentences, front-loaded with purpose and then the practical constraints; every clause carries information. Slightly dense and could be split for scannability, but there is no redundant filler.

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?

No output schema exists, so the description carries the return-value burden and does so by naming the priced components and conditional delivery estimate. It leaves error/edge-case behavior (invalid coupon, postal code outside Canada, unavailable variants) unspecified.

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?

With only 33% schema coverage, the description compensates well: it explains that variant_id values originate from search_products, that coupon_code is optional, and that postal_code drives the delivery estimate (the one field already documented in schema). It does not explain qty limits (1-20 per item, 20 items max), which remain schema-only.

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 specific verb and resource ('Price a cart') and enumerates the outputs (line prices with sale/quantity breaks, coupon, shipping, CAD total, delivery estimate), which separates it cleanly from siblings like create_cart_link and delivery_estimate. The scope note 'exactly as Deer Supply's checkout would' pins the semantics.

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 usage context: postal_code triggers a delivery estimate, variant_id must come from search_products, and 'Nothing is reserved or ordered' tells the agent this is a read-only quote rather than a purchase step. It does not explicitly name a when-not alternative (e.g., create_cart_link), so it falls short of a 5.

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