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

No annotations are supplied, so the description carries the full disclosure burden. It does explain the distinctive emergent behavior — bell curves, S-curves and dips arise from level values rather than being set directly — which is genuinely useful. However, it never says whether the chart is persisted, shareable, or editable afterward, which matters for a creation tool with a sibling edit_chart.

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?

Three short sentences, front-loaded with what the tool produces, then when to use it, then the binding constraint. No filler or repeated schema content.

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 five-parameter tool with nested arrays and no annotations or output schema, the description explains structure and rendering well enough to call correctly. The remaining gap is lifecycle behavior after creation (persistence, returned identifiers, subsequent editing), which the agent must infer.

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 100%, so the baseline is 3; the description earns above that by adding meaning the schema lacks — that levels 1-10 combine to produce recognizable curve shapes, and that phaseId linkage is mandatory for every milestone. It does not cover timeLabel, curveLabel or key, but the schema already does.

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?

Names a specific verb and resource ('Create a lifecycle chart') and immediately describes the rendering model: phases across the top, milestones on a curve. The use-case clause (product lifecycles, customer journeys, adoption curves) implicitly separates it from timeline/chevron siblings, but no sibling is named or explicitly excluded.

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 context for when to reach for this chart type via three concrete use cases, plus a hard prerequisite ('Every milestone needs a phaseId'). It stops short of stating when-not-to-use it or naming an alternative such as create_timeline_chart.

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