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

Adds real context beyond annotations: required READ:PURCHASE scope, amounts in smallest currency unit, default 3-year window, and the pagination round-trip contract. Annotations already cover read-only safety, so this adds the operational details an agent otherwise couldn't guess.

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?

Two dense sentences with zero filler, ending with the endpoint path. Slightly crowded – auth, unit convention, window default and pagination are all packed into one long run-on – but each clause carries information.

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?

Covers auth, unit conventions, default time window, pagination loop, and the payload contents, which is what an agent needs to call this correctly without an output schema. Only the ordering default vs. the descending parameter interaction could be stated more explicitly.

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 baseline is 3; the description goes further by explaining the pagination protocol (pass next_page_hash back as last_purchase_hash with identical other arguments), which the schema alone does not make clear.

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?

Specific verb + resource (list POS purchases, sales and refunds) plus a concrete enumeration of the fields returned. Clear distinction from the read-one sibling zettle_get_purchase is implied by 'list' vs 'get' and the pagination mention.

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?

States the default window (last 3 years) and the prerequisite scope READ:PURCHASE, but never says when to use this versus zettle_get_purchase or zettle_list_account_transactions. Usage is only implied by the resource it operates on.

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