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

With no annotations, the description carries the full burden. It discloses important methodology: 79 months of survey prices, removal of price-increase effects, and isolation of monthly patterns. This is meaningful behavioral context beyond a simple 'returns seasonal calendar'.

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 and front-loaded: the first sentence states the core question, the second defines the resource, and the third adds methodology and usage context. Every sentence earns its place without redundancy.

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 zero-parameter tool with no output schema, the description provides sufficient context about what the tool answers, how it was computed, and when to use it. It does not describe the exact return format, but the purpose and domain are clear enough for the agent to invoke it appropriately.

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 tool has zero parameters, so the baseline is 4. The description adds conceptual meaning by explaining that the calendar works per product category ('品目ごと') and is derived from detrended monthly data, which helps an agent understand its scope even with no explicit input 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 identifies what the tool does: it answers which month is cheapest for a given item and presents a seasonal buying calendar by product category. It also distinguishes itself through its seasonal/monthly pattern focus, though it does not explicitly name sibling alternatives.

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 explicitly states when to use it: for consultations about 'vegetables being cheap', 'seasonality', and 'good time to buy'. It does not provide exclusions or mention alternative tools, but the use case is clear enough for an agent to route to it.

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