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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety and scope are covered. The description adds genuinely non-redundant behavior: how similarity is computed (brand/category/part-number prefix) and the capped result size. It stops short of describing ordering/ranking of suggestions or what is returned when nothing matches.

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 short sentences, no filler, with the core action and the similarity rule front-loaded before the situational guidance and the cap. Every sentence carries information the agent can use.

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 lookup with a fully documented schema and no output schema, the description covers action, matching logic, and result cap adequately. The notable gap is that zero parameters are required, yet the description never says what happens if neither sku nor part_number is supplied, or how suggestions are ranked/ordered.

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 every parameter including the sku/part_number alias and the brand_shop enum is already documented. The description's only parameter-adjacent content, 'Max 20', merely restates the schema maximum. Baseline 3 applies since the schema does the heavy lifting.

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 ('Suggest similar/alternative parts for a SKU') and goes further by defining the similarity basis (same brand/category/part-number prefix), so the agent knows what counts as an 'alternative'. It does not explicitly contrast itself with search_parts or get_part, so sibling differentiation is implied rather than stated.

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?

'Useful when the exact type is unavailable or for cross-checks' gives two concrete triggering situations, which is solid when-to-use guidance. There is no explicit when-not or named alternative tool for the case where the caller wants an exact match, so it falls short of a 5.

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