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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data rather than the description. The description contributes one useful behavioral detail beyond the schema — that variants are included in the result — plus the underlying GET endpoint. It says nothing about error behavior for a missing id or about permissions.

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 that front-loads the action and resource, then appends the endpoint reference. Every clause earns its place; nothing is padded.

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 one-parameter read tool with no output schema, the description covers what is needed: what is fetched, the keying identifier, and the fact that variants come along. The absence of an output schema means the return shape is only loosely hinted at, keeping it short of a 5.

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?

With a single parameter and 100% schema description coverage ('The item id (UUID).'), the schema already carries the full parameter burden. The description's 'by id' adds no format or constraint detail beyond it, so the 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 a single catalog item by id, with its variants.' The word 'single' implicitly contrasts with the sibling loyverse_list_items, but no alternative is named outright. Clear and unambiguous, though not maximally sibling-differentiated.

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 by 'by id' and 'single' — an agent can infer it is for direct lookups when a UUID is known — but there is no explicit when-to-use, when-not-to-use, or pointer to loyverse_list_items for browsing. Guidance exists only by inference.

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