Calculate and reserve multiple coupons

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

Annotations only flag readOnlyHint=false and non-idempotency; the description adds the genuinely non-obvious behavior that all supplied codes must be eligible and applied (all-or-nothing failure) and how stacking order changes the outcome. It stops short of saying whether a reservation persists, how long it lasts, or how partial failures surface.

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 sentences, each load-bearing: scope first, strategy semantics second, eligibility contract last. No filler and no repetition of schema structure.

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?

A deeply nested 4-parameter tool with 0% schema description coverage and no output schema needs more than strategy hints; the description never explains what the context object is for or what a successful quote returns. Only the smallest parameter (selection) is meaningfully documented.

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 0%, so the description must carry parameter meaning. It usefully explains the two selection.strategy values and the 2–10 code bound, but says nothing about context (cart, user, unit_id, brand_id, location, shipping, payment_method) or cart_id, which is the bulk of the schema.

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 uses a specific verb pair ('Validate and calculate') plus a clearly scoped resource ('2–10 known coupon codes'), which distinguishes it from quote_single_coupon by cardinality. It does not explicitly name the sibling it replaces, so the differentiation is implied rather than stated.

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?

'Known coupon codes' and the 2–10 bound imply when this tool applies versus discovery siblings like find_eligible_coupons, but that routing is never made explicit. No statement tells the agent when to prefer quote_single_coupon or what prerequisite state (e.g. an existing cart) is required.

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