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

Annotations already declare readOnlyHint=true, so the safety profile is partly covered, but the description goes further by enumerating what is out of scope (no writes, no basket, no checkout, no order/payment operations). It also discloses the computation pipeline (receipt mining → assortment resolution) and the fields returned, which annotations alone do not convey.

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 ordered as question → mechanism/output → safety boundary, with zero filler. Each sentence earns its place and the most decision-relevant context (the user question) is front-loaded.

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 burden of describing returns and does so fully: offer price (was/now), discount, promo type, validity window and unit price. Combined with the explicit read-only scope, an agent has everything needed to call and interpret it.

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 the schema already documents all four parameters including defaults and bounds. The description hints at the frequency-mining semantics (purchase frequency over recent receipts) but adds no syntax or format detail beyond the schema; baseline 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?

States a concrete verb chain (mines receipts, resolves items, reports offers) and the exact resource: currently promoted items among frequently purchased products. The compound behavior is spelled out, making it clearly distinct from jumbo_search_products (assortment lookup) and jumbo_search_receipts (raw receipt search).

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?

The lead framing 'of the things I actually buy, what is on offer right now?' gives a clear use context that separates it from raw product/receipt search tools. It does not explicitly name or exclude the sibling alternatives, so it falls short of the 5-level routing guidance.

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