Sankey Diagram

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety and idempotency. The description adds no behavioral details beyond the chart's visual mapping, which is consistent but not supplementary.

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, no redundancy. The first sentence clearly states the action and concept; the second lists use cases. Every word is purposeful and front-loaded.

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?

For a rendering tool with 7 parameters (2 required) and no output schema, the description adequately explains the chart type and typical applications. It could mention that the output is a rendered image, but the purpose is clear enough.

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 86%, meaning most parameters are well-documented in the schema. The description adds minimal parameter-level value (only implicitly explains 'flow' width). 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 explicitly states 'Render a sankey flow diagram' and explains the concept with 'Where does it go? Shows flows between nodes with width proportional to value.' It lists specific use cases (budget flows, user journeys, etc.), clearly differentiating from other chart siblings.

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 clear use case examples ('Great for budget flows, user journeys, energy transfers, conversion funnels'), giving the agent context on when to use this tool. However, it lacks explicit when-not-to-use guidance or direct comparisons to alternative chart types among siblings.

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