prepare_chart_data

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

With no annotations provided, the description carries the full disclosure burden. It reveals that the default return is only OHLCV, describes the response format, notes that JPY pair prices are rounded to integers, and explains tz behavior for local time conversion. However, it does not explicitly state that the tool is read-only or destructive, though the context implies read-only. A mention of authorization or rate limits would elevate it further.

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 relatively long but well-structured, with a clear title line, bullet-point warnings, and separate notes on response format and tz. It front-loads the purpose and critical usage constraints. Minor redundancy: 'デフォルトはローソク足（OHLCV）のみ返す。indicators 未指定 = ローソク足のみ。' repeats the same message. Overall, each sentence earns its place.

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's complexity (5 parameters, no output schema, many sibling tools), the description is quite complete. It explains the response format, default behavior, and tz effect, and references sibling tools for related tasks. However, pair and type parameters are not explained (only defaults in schema), and the absence of an output schema means the agent relies entirely on the description for return understanding. Still, the provided information is sufficient for most use cases.

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?

Schema description coverage is only 20%, so the description must compensate. It does so effectively for tz (explains local time and labels), limit (warns about default and when to increase), and indicators (lists allowed values and emphasizes explicit specification). However, pair and type receive minimal elaboration beyond defaults. The description adds significant meaning beyond the schema for three of five parameters.

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 as the first-choice for chart drawing (candlestick/visualization). It specifies that it returns OHLCV data with optional indicators and distinguishes from sibling tools like render_chart_svg and analyze_indicators. The verb 'prepare_chart_data' is specific and the resource is well-defined.

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 provides explicit guidance on when to use this tool (first choice for charting) and when not (e.g., for SVG/PNG files use render_chart_svg; for indicator analysis use analyze_indicators). It includes critical warnings: default limit 30, only increase if user specifies a period; only specify indicators if user explicitly requests; and caution about context consumption. This fully addresses usage context.

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