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

Annotations already declare read-only, open-world, non-destructive behavior. The description adds useful operational context: PNG output, external Darwin/AntV rendering, 50-row limit, bounded image sizes, and no API key or payments.

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?

Two sentences, front-loaded with the core purpose and key constraints. Minor redundancy in "such as, comparing categorical data and for horizontal comparisons" keeps it from being maximally tight.

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?

Output schema and annotations cover return values and safety profile, so those need not be in the description. However, with 10 parameters, nested style options, and low schema coverage, the description is too thin on parameter usage details for full completeness.

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 30% across 10 parameters. The description only indirectly mentions the 50-row data cap and bounded image sizes; it does not explain group/stack/style/theme/title/axis parameters or how they interact.

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?

States a specific verb and resource: "Generate a horizontal bar chart." The horizontal orientation clearly distinguishes it from generate_column_chart, and the comparison purpose is explicit.

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?

Gives clear usage context: numerical comparisons among categories and horizontal comparisons. It does not explicitly say when to choose generate_column_chart or generate_line_chart instead, but the intended use case is clear.

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