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

The annotations already declare read-only, open-world, and non-destructive behavior, but the description adds important context about what the image contains, that no indicators are drawn, that charts update every minute from the TraderWAI feed, and that the feed may differ from the user's broker. It also discloses image weight and copyright/redraw restrictions, which materially affects how an agent should use the tool.

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 front-loaded with purpose and usage, and nearly every sentence carries actionable guidance. It is somewhat long due to the list of visual patterns and multiple usage warnings, but the length is largely justified by the complexity of the tool.

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?

There is no output schema, so the description must explain the return value, and it does: a pre-rendered candlestick chart image with candles, separators, and last price but no indicators. It also covers update cadence, data-source caveats, and the related drawing workflow, leaving little ambiguity for an agent calling this tool.

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 100%, and the schema already documents the symbol and timeframe parameters. The description adds usage context around timeframes, but it does not add parameter syntax or format details beyond the schema, so the baseline score of 3 is appropriate.

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 states a specific verb and resource: it returns a pre-rendered candlestick chart image for a symbol and timeframe. It also distinguishes itself from nearby tools such as get_ohlc, get_quote, and draw_chart, so an agent can tell what this tool uniquely provides.

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?

It explicitly says to use the chart for visual market structure and context, starting with a higher timeframe and then the entry timeframe. It also gives clear exclusions: do not read exact prices from the image, use get_ohlc and get_quote instead, avoid using it on every message, and call draw_chart when the user wants levels or setups drawn.

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