主要マクロ指標スナップショット

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

With no annotations, the description carries the full burden of behavioral disclosure. It states the data source (Yahoo Finance), the delay (約1時間遅れ), and a disclaimer (参考値、投資助言ではありません). This provides good transparency about the tool's read-only nature and data limitations, though it does not mention error handling or rate limits.

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 a single paragraph that front-loads the list of indicators, then concisely states the source, delay, and disclaimer. Every sentence adds value, with no redundant or unnecessary words.

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 the tool has no parameters and no output schema, the description is nearly complete. It explains what the tool does, what data it retrieves, the source, and the limitations. However, it does not describe the output format (e.g., JSON structure), which could be useful for an agent to parse the response.

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 description does not need to add parameter semantics. According to the guidelines, 0 parameters merit a baseline of 4. The description does not repeat schema information, and there are no parameters to document.

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 lists all 28 major indicators (e.g., USD/JPY, 日経平均, S&P 500) and states it retrieves their current values and day-over-day changes from Yahoo Finance. This is a specific verb+resource combination that clearly distinguishes it from sibling tools that retrieve individual quotes or sector heatmaps.

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 implies the tool is for a broad market snapshot, but it does not explicitly state when to use it over alternatives like get_quote or get_market_thermometer. There is no exclusion or alternative naming, so usage guidance is only implied by the tool's scope.

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