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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered externally. The description contributes the useful detail that the response spans contact data, debt, invoiced totals, reward points and groups. It says nothing about not-found handling or error behavior for a live external API.

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 fragments front-load the resource scope and then the endpoint. Every element earns its place: the field list is informative and the endpoint gives an integration anchor, with no 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 read tool with full schema coverage and annotations, this is largely sufficient, and the field enumeration compensates for the absence of an output schema. The only meaningful gap is undefined behavior when the customer id does not exist.

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% and the single parameter is already documented as 'KiotViet customer id' with a positive-integer constraint. The description's 'by id' merely restates that framing; it adds no format or sourcing guidance beyond the schema. Baseline 3 applies.

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 (fetch one customer) and the scoping key ('by id'), which implicitly separates it from kiotviet_get_customer_by_code and kiotviet_list_customers. It also enumerates the payload categories returned. It stops short of explicitly naming the sibling tools it is not.

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?

Usage is implied rather than stated: an agent can infer this is the lookup path when a numeric id is available, and the 'by id' phrasing hints at the code-based alternative. There is no explicit when-to-use / when-not-to-use rule and no mention of what to do if the id is unknown.

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