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

With no annotations, the description must carry the full behavioral burden. It discloses the filtering logic (2kg or less), the sorting order (descending by content per 10,000 yen), and the data source (reading from product names, excluding unreadable ones). It doesn't mention error handling or no-result behavior, but the core behavior is transparent. A small gap remains regarding what happens when no items match.

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, using one sentence with clear clauses. It front-loads the purpose and immediately provides usage criteria. Every clause adds value: filtering, sorting, data extraction rule, and usage triggers. No 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 filter-and-sort tool with no output schema, the description is fairly complete: it defines what it filters, how it sorts, and when to use it. It could specify whether results are limited or how many items are returned, but given the tool's simplicity, this is a minor gap. The description covers the essential context an agent needs.

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 there is no schema to describe. The baseline for 0 params is 4. The description implicitly defines the query scope via keywords, but since no parameters exist, no additional parameter semantics are needed.

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: it filters furusato nozei return gifts for single-person households, limits to 2kg or less, and sorts by content amount per 10,000 yen. It also provides specific usage triggers ('一人暮らし', '少量', etc.), distinguishing it from generic furusato tools. This is specific and actionable.

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 this tool: for consultations involving 'living alone', 'small amount', 'amount you can eat', or 'one person'. It doesn't name alternatives, but the trigger phrases effectively route the agent to this tool over siblings like furusato or furusato_index.

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