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

With no annotations provided, the description carries the full burden and does so excellently. It discloses rotation fit, automatic coordination plan generation, carry_in route checks for large items, risk level handling (warning/critical), and the requirement to present affiliate_url. These are behavioral traits beyond a simple search action and help the agent understand what to expect and what actions to take.

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?

The description is compact but information-dense, covering the trigger, core behavior, special features, and necessary user-facing actions in just a few sentences. Every sentence adds value, with no padding or repetition. It is front-loaded with the primary use case, making it easy to scan.

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?

Given there is no output schema and no annotations, the description compensates by describing return values (products, coordination plans, carry_in info, affiliate_url) and instructs the agent on how to handle risk levels and present affiliate links. It covers all critical aspects of the tool's behavior for an agent to invoke and use it correctly.

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?

The input schema already provides descriptions for all parameters, giving 100% coverage, so the baseline is 3. The description adds little parameter-specific meaning beyond confirming dimensions are in mm and that rotation of width/depth is considered—which is more of a behavioral trait. It does not clarify any parameter ambiguities beyond the schema.

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 clearly states the tool's purpose with a specific verb and resource: it suggests products that fit in a space based on dimensions. It distinguishes itself from siblings by explicitly saying this is for 'space-based' searches (スペース起点で探すとき) and describes cross-category return behavior. The concrete example ('洗面所の幅45cm×奥行30cmの隙間') makes the use case unmistakable.

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?

It provides a clear when-to-use trigger: call when searching with space as the starting point, with a concrete example. However, it does not explicitly name alternative tools or state when not to use this tool, so it stops short of full guidance. The context is clear enough for an agent to distinguish from general product searches.

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