Interpolate cel positions between frames with deterministic easing. Set start/end coordinates, frame range, and easing type to generate in-between placements.
Tween cel positions across frames with deterministic easing.
| Name | Required | Description | Default |
|---|---|---|---|
| end_x | Yes | ||
| end_y | Yes | ||
| easing | No | smoothstep | |
| start_x | Yes | ||
| start_y | Yes | ||
| filename | Yes | ||
| end_frame | Yes | ||
| layer_name | Yes | ||
| start_frame | Yes | ||
| source_frame_index | No | ||
| create_missing_cels | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description must carry the full burden of behavioral disclosure. It only mentions 'deterministic easing', which hints at predictable interpolation but does not disclose that this is a mutation operation, how existing cels are handled, or the effect of parameters like 'create_missing_cels'. The operational impact on the animation is left entirely unspecified.
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 a single concise sentence, but it is under-specified. It functions more as a title than a description, providing no structured information or front-loaded critical details. While concise, it sacrifices all substance.
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 tool with 11 parameters (8 required) and no output schema or annotations, this description is grossly incomplete. An agent cannot infer how to set easing, what 'source_frame_index' does, or whether 'create_missing_cels' is necessary. The description fails to provide any context needed for correct invocation.
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 0%, so the description must compensate by explaining parameters. It mentions none. The schema lists many fields (easing enum, source_frame_index, create_missing_cels, coordinates, frames) with no descriptions, and the description adds no meaning to any of them. An agent has zero guidance on how to set these 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?
The description uses a specific verb ('tween') and resource ('cel positions') and adds a distinguishing feature ('deterministic easing'). It clearly indicates the tool's function and hints at a differentiator from the sibling 'tween_cel_positions'. However, it does not explicitly contrast with that sibling or explain what 'deterministic' implies beyond a vague promise of predictability.
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?
No guidance is provided on when to use this tool versus alternatives like 'tween_cel_positions' or 'tween_cel_opacity_eased'. The description only states what it does, not when to choose it. There are no exclusions or conditions that would help an agent select between the tween variants.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.