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

Annotations already declare readOnly/idempotent/non-destructive safety, and the description layers on substantial behavioral context: the exact ranking metric (effective_total using shelf or universally-open promotions), the distinction between shelf_total and club_total, coverage/missing reporting, and the free-text-plus-quantity/barcode input model. This is well beyond what annotations alone 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?

The key scoping and ranking facts are front-loaded in the first sentence, and subsequent sentences each add distinct information (per-branch fields, input syntax, the site-link handoff). It is dense and slightly long, but no sentence is redundant.

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 thoroughly — enumerating effective_total, shelf_total, club_total, coverage, missing, and the try_it_on_site link. Nothing an agent needs to call or interpret this tool appears to be 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 schema documents both params, but the description still adds real meaning: items are free-text Hebrew names with optional quantities ("במבה x3") or barcodes, and each is matched to a product exposed via items[].matched. The schema's numeric limits (maxLength 80, maxItems 40) are not echoed, so it is not exhaustive.

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 gives a precise verb+resource+scope: pricing an entire shopping list across every supermarket branch of a named city and returning the 5 cheapest. It distinguishes itself from siblings such as cheapest_stores_in_city and compare_basket_by_chain by framing the result set (5 cheapest branches) and the ranking metric (effective_total).

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?

It states the trigger intent explicitly: "Use this for 'where is my shopping cheapest in <city>'." That is clear context for when to reach for it, but it does not name a sibling alternative or an exclusion (e.g., when to use cheapest_stores_in_city instead).

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