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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds real value beyond them: no stock reservation, no charge, tax excluded and deferred to checkout, and that it runs validation on products, variants and personalization. It stops short of describing failure behavior or whether all shipping options or one is returned when unspecified, so 4 rather than 5.

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?

A single dense sentence front-loads the core action and follows with behavioral caveats; every clause (validation, offers, shipping options, pre-tax total) carries information an agent needs. No redundant restatement of the title or name.

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?

With no output schema, the description usefully discloses the return content (shipping options, total before tax). For a nested 4-parameter tool it is nearly complete but omits failure/error semantics for invalid products or personalization, which matters given validation is a stated function.

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 only 25%, so the description should compensate more than it does; it does convey that a coupon or an automatic multi-buy offer affects pricing and that shipping options are surfaced, which maps to coupon_code and shipping_option. But it adds little about item-level semantics (quantity limits, why variant_id vs options) or the US-only address constraint, leaving those to the schema text.

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 ('Price') and resource ('a prospective order'), then enumerates the operations performed (validating products/variants/personalization, applying offers or coupons) and what is returned (shipping options, pre-tax total). None of the siblings (browse/get/list/search) do anything similar, so an agent can identify this as the pricing tool without ambiguity.

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?

Context is clear: use it for a 'prospective order' before checkout, since tax 'is calculated at checkout'. The closing sentence implicitly steers actual purchase creation elsewhere by stating it does not create an order. It never explicitly names a when-not-to-use condition or compares to a checkout tool, which keeps it from a 5.

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