Add an animation timeline to a sketch to control global duration, FPS, and looping, enabling consistent motion timing for exports.
Add an animation timeline to the sketch (sets global duration, fps, and loop).
| Name | Required | Description | Default |
|---|---|---|---|
| fps | No | Frame rate for export. 1–60. Default 30. | |
| loop | No | Whether the animation loops. Default true. | |
| duration | No | Total duration in seconds. Default 3.0. |
Changes observed during successful MCP inspections.
v0.5.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It says it adds a timeline and sets globals, but does not disclose whether an existing timeline is replaced, whether this requires an open sketch, what happens on failure, or what the tool returns.
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?
It is a single front-loaded sentence with zero filler: verb, resource, target sketch, and the three controlled settings. The parenthetical is compact and useful.
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?
The fully documented schema makes the tool callable, but with no annotations and no output schema the description should say more about mutation behavior (create vs replace), return values, and preconditions. It is minimally adequate rather than complete.
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 100%, and the schema already documents fps range/default, loop default, and duration default. The description names the same three settings but adds no extra meaning such as constraints or interactions.
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 states a specific verb and resource: 'Add an animation timeline to the sketch', and clarifies the timeline-level settings it controls (duration, fps, loop). It is distinguishable from keyframe tools, though it does not explicitly name sibling alternatives.
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?
There is no guidance on when to use this tool versus alternatives such as design_set_keyframe or design_get_style_timeline, nor any prerequisites such as whether a sketch must already be open. The intended setup role is only implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.