米株セクター ETF 前日比ヒートマップ（SPDR、11 セクター）

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

No annotations are provided, so the description must bear the full burden. It clearly indicates this is a read operation (取得 - get) and specifies the data (current price and day-over-day change). However, it does not explicitly confirm idempotency, mention whether it calls external APIs, or describe any rate limits. The behavior is implied but not fully disclosed.

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 only two sentences, both dense with information. The first enumerates exactly which ETFs are included and what data is returned; the second provides context for use. Every word is purposeful with 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?

The tool has no parameters and no output schema. The description identifies inputs and purpose but does not describe the output structure or format (e.g., JSON with ticker, price, change). For a tool this simple, the missing output details reduce completeness. It is adequate but not fully self-contained.

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 has zero parameters, so the baseline is 4. The description adds value by listing the specific ETFs, which effectively defines the fixed scope of the tool, but since there are no parameters to describe, the score meets the baseline.

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 explicitly states the tool retrieves current prices and day-over-day changes for 11 specific US sector ETFs (SPDR). The verb '一括取得' (batch get) is precise, and the resource is fully enumerated. This clearly distinguishes it from sibling tools like get_quote which likely handles single quotes.

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 notes the tool is a 'source for understanding US stock market sector rotation', implying usage for market analysis. However, it does not explicitly state when to use this versus alternatives like get_quote or get_market_snapshot, nor does it provide any when-not-to-use guidance.

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