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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds genuine behavioral context beyond that: default sort order (newest first) and the aggregate fields returned per customer. It stops short of describing pagination flow, though the cursor parameter schema covers that.

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 compact sentences with the key behavior (ordering, returned fields) front-loaded and no filler. The trailing 'Loyverse: GET /customers' is marginal restatement but is short and harmless.

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 usefully enumerates the prominent returned fields (visits, total spent, points balance), compensating for the missing return contract. All 8 parameters are covered by the schema, so an agent has enough to invoke it correctly.

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 8 parameters with examples. The description only echoes the email/ids filters and adds nothing about limit, cursor, or the created/updated time bounds. Baseline 3 is appropriate when the schema carries the load.

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 (list) and resource (loyalty customers), and adds valuable detail about sort order ('newest first') and returned fields ('visits, total spent and points balance'). It does not explicitly distinguish itself from the singular sibling loyverse_get_customer, though 'List' vs 'get' implies the distinction.

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 when the tool is useful for lookups, but there is no explicit when-to-use/when-not guidance and no routing to the alternative loyverse_get_customer for single-record fetches. Usage is implied rather than stated.

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