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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds meaningful context: results are limited to stores with current cashback offers, the list can run to hundreds of stores, rates are excluded, and response fields such as has_gift_cards and gift_cards_url are disclosed. It also adds presentation guidance about rendering URLs as clickable links.

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?

Core behavior is front-loaded in the first sentence; use cases, exclusions, and alternatives follow logically; and the presentation instruction is the only trailing detail. Every sentence adds a distinct operational fact without repetition or filler.

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?

For a single-parameter readonly list tool with an output schema, te description covers scope, intended usage, exclusions, sibling alternatives, supported-code lookup, list size expectations, and result presentation behavior. Nothing needed to invoke or present the tool 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?

The input schema fully documents country_code with format, examples, the 'gb not uk' caveat, and a pointer to get_countries, so the schema carries the parameter-semantics load. The description reinforces that the parameter represents the country to browse but adds no new parameter-level detail.

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 and resource: 'Lists every store ... in one country' and defines the exact scope: stores with current cashback offers, identity, store page url, gift-card presence, and no rates. This clearly distinguishes it from sibling store-name lookup tools.

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?

Gives explicit when-to-use guidance ('when the user wants to browse or count what is available in a country') with example queries, and explicit do-not-use guidance for finding a particular store or its rates, naming get_cashback_rates_by_store_name and get_gift_cards_by_store_name as alternatives. It also directs callers to get_countries for supported codes.

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