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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely useful behavioral context the annotations do not: the sort order (newest first) and the fact that each record carries visits, total spent and points balance. It stops short of describing pagination limits or rate behavior.

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 compact sentences with zero filler; the scope, sort order and return payload are front-loaded before the filter hint and the API endpoint reference.

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 read-only list tool with no output schema, the description discloses the salient return fields and ordering, which is what an agent most needs. Minor gaps remain around paging behavior and whether an empty filter returns the full customer set, but the definition is largely self-sufficient.

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 every parameter (email, limit, cursor, customer_ids, the four timestamp bounds) is already documented in the schema. The description's 'filter by email or ids' restates two of them without adding syntax or format detail, so it earns only the baseline 3.

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 ('List loyalty customers') plus the returned fields (visits, total spent, points balance) and sort order ('newest first'). It implicitly distinguishes itself from the sibling loyverse_get_customer by being the plural/list variant, but never names that sibling explicitly, so differentiation requires a small inference.

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?

'Filter by email or ids' hints at how to narrow results, but there is no statement of when to use this list tool versus loyverse_get_customer for a single record, nor any note on pagination workflow beyond what the schema implies. Usage is implied rather than prescribed.

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