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 real value beyond that by enumerating the payload contents (visits, total spent, points balance) and citing the underlying endpoint GET /customers/{customer_id}, which matters because no output schema exists.

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?

One compact sentence front-loads the action, scope, and return fields, with the endpoint reference appended. Nothing is padded and nothing important is buried.

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 single-record fetch with no output schema, the description compensates adequately by listing the notable returned fields. Minor gaps remain around error behavior for unknown ids and whether related records are paginated, but the core need is met.

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% and the single parameter has its own description identifying it as a UUID, so the schema does the heavy lifting. The description only adds the redundant 'by id' framing; baseline 3 applies for a one-parameter tool with full schema coverage.

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 (fetch) and resource (a single customer) and names the exact returned fields. The word 'single' distinguishes it cleanly from loyverse_list_customers in the sibling set.

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?

The phrase 'fetch a single customer by id' implies this is the one-at-a-time counterpart to loyverse_list_customers, but no alternative is named and no condition is given for choosing between them. Usage is inferable rather than stated.

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