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

Annotations already declare readOnlyHint/idempotentHint, so the 'never changes a price' line is largely reinforcement, but the description earns its keep by adding the fallback scope (contested listings when sku is omitted) and by telling the agent that `narrative` is the answer field. It does not discuss rate limits or freshness of the Pricing API data.

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 core definition is front-loaded in the first clause and every later sentence adds routing or scope information. The sentences are long and multi-clause, and the explicit read-only restatement partly duplicates the annotations, costing a bit of tightness.

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 carries the return-value burden and does so: price-to-win versus current featured offer, reference prices, and the economics overlay (contribution per unit, break-even ACoS at that price), plus the `narrative` answer field. Nothing an agent needs to call this correctly is missing.

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 100%, so the baseline is 3, and the description adds a business-level gloss on the sku parameter: omitting it means checking the SKUs where another seller occupies the listing, which is more actionable than the schema's 'contested listings'. account and marketplace_id are left entirely to the schema, which is acceptable given their clarity.

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 names a specific resource (the Buy Box price / featured-offer threshold from Amazon's Pricing API) and enumerates exactly what comes back per SKU: the price to win, the competing offer holding the Box, and Amazon's reference prices. It is clearly separable from siblings like get_buybox_status (status, not price) and get_amazon_bid_recommendations (ads bids, not listing price).

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?

Three concrete question phrasings anchor when to use it ('what price wins the Buy Box back', 'why was my deal rejected for no reference price', 'can I afford to match'), plus the default behavior when no sku is passed is stated. It also routes the write case away explicitly: draft_price_change does the mutation, with approval.

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