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

Annotations already flag destructiveHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds genuine value beyond that by disclosing PATCH semantics — "only the fields you pass are changed" — and that passed values overwrite existing ones, which the annotations do not convey. It stops short of mentioning auth/permission needs or failure modes.

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, front-loaded with the WRITE marker and the partial-update rule, then the overwrite consequence, then the endpoint. No filler and nothing 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 22-parameter mutation tool with full schema coverage and rich annotations, the description covers what matters most: it is a write, it is a partial update, and it overwrites. What is missing is how to source the product_id and any contract-level caveats (e.g., division changes requiring specific contract features), which the schema hints at but the description does not reinforce.

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 every one of the 22 parameters carries its own description (including enum-like meanings for division, taxDivision, salesDivision), so the schema does the heavy lifting. The description only gives "price or name" as illustrative examples and adds no format, constraint, or interaction detail beyond the schema. Baseline 3 is appropriate.

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?

"WRITE: change fields of one product" gives a specific verb (change/update), resource (one product), and scope (single record), plus the HTTP verb and path (PATCH /products/{product_id}). It is unmistakably distinct from sibling smaregi_create_product and smaregi_update_customer without needing to open any 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?

The description establishes the update context and implicitly distinguishes itself from creation by saying "change fields of one product," but it never explicitly says when to use this over smaregi_create_product, nor how to obtain a valid product_id (e.g., via smaregi_list_products or smaregi_get_product). Usage is implied rather than stated.

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