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

No annotations are provided, so the description must carry the full burden. It discloses that this is a server-side generation tool and prohibits spontaneous calls. However, it does not describe the return format (e.g., raw SVG string, file path, or PNG binary), nor potential side effects, error handling, or limits. Some behavioral context is given but incomplete.

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 brief and front-loaded with the most critical information: purpose, alternative tool, and usage constraints. Every sentence adds value. It could be slightly more structured, but overall it is concise and effective.

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 (22 parameters, nested objects, no output schema), the description is somewhat incomplete. It lacks details on the return output (SVG/PNG specifics), error conditions, and parameter formatting beyond indicators and overlays. However, it does adequately address usage context and primary purpose. A more complete description would cover what the agent receives after calling the 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 only 41% (low), so the description should compensate. The description adds meaning for the 'indicators' and 'overlays' parameters by specifying usage conditions, but it ignores the other 20+ parameters. For instance, it does not explain the meaning of 'bbMode', 'ichimoku', or 'subPanels' in natural language. This insufficiently aids an agent to fill parameters correctly.

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?

Description clearly states the tool generates candlestick/line charts as SVG/PNG on the server side. It specifically distinguishes itself from prepare_chart_data, noting that client-side rendering should be preferred. The verb 'generate' and resource 'SVG/PNG' are explicit, and the scope (candlestick/line chart) 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?

Excellent usage guidance: explicitly instructs to use only when user requests SVG/PNG save, prohibits spontaneous calls, and prioritizes prepare_chart_data for client-side rendering. Additionally, it specifies that indicators should only be added when the user explicitly requests them, with defaults off. This provides clear when/when-not to use and even names the sibling tool.

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