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

Annotations are sparse (readOnlyHint=false, openWorldHint=true), so the description carries the behavioral burden. It discloses that the tool can both render the existing chart and build one from provided parameters, and it warns that pixels are for shape while exact numbers should come from figures or data tools. This is useful beyond the annotations.

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 and front-loaded: purpose first, then usage guidance, then a practical caveat about numeric precision. Each sentence earns its place, and there is no filler.

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?

With no output schema, the description usefully mentions that the response includes both a PNG and the exact figures shown. It also covers the two usage paths and the main parameter groups. It stops short of detailing response structure or persistence effects of one-call building, but these are not critical gaps for typical invocation.

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 coverage is high at 75%, and the description reinforces the meaning of key parameters by explaining that symbol, timeframe, indicators, and levels can be passed to build a chart in one call. It adds workflow context without needing to restate the schema's field-level descriptions.

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 names the specific resource (a PNG of the current chart) and its exact contents: candles, volume, indicators, drawings, and the figures it displays. It also distinguishes the tool from sibling chart tools by framing it as the way to 'see' what has been built.

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 clearly says when to use the tool ('to check structure, levels and what you drew before you describe them') and explains the two entry modes: build first with chart tools, or pass symbol/timeframe/indicators/levels to build and view in one call. It does not explicitly name an alternative tool, but the guidance is clear enough.

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