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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is handled. The description adds only the underlying REST path (GET /admin/variants/{id}.json), which is mild context; it says nothing about error behavior for missing ids or rate limiting.

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 short fragments, zero filler, with the scope statement front-loaded. It is at the edge of under-specification rather than verbosity, but nothing is wasted.

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 full annotation coverage and a fully described schema, the definition is minimally sufficient to call correctly. It omits what a caller would want next – not-found behavior and response shape – though the absence of an output schema means return values arguably need not be described.

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 variant_id parameter is already documented in the schema with type and bounds. The phrase 'by id' adds no syntax or format detail beyond that, so the baseline 3 for schema-covered parameters 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?

The description names a specific resource ('product variant') and narrows scope to a single record fetched by id, which implicitly separates it from the sibling sapo_list_product_variants. It does not name the sibling explicitly, but an agent can tell single-fetch from list without opening the schema.

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: retrieve one variant when you already have its id, versus listing variants. There is no explicit 'use this instead of...' statement or precondition about what to do when the id is unknown or the variant does not exist.

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