Add a null object in After Effects for parenting or rigging, with optional 3D and position settings, targeting a named composition or the active comp.
After Effects: add a null object (for parenting / rigs), optionally 3D and positioned.
| Name | Required | Description | Default |
|---|---|---|---|
| name | No | ||
| threeD | No | ||
| position | No | ||
| compositionName | No | Comp name; omit to use the active comp. |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this is a non-read-only, non-destructive, closed-world mutation, so the safety profile is covered. The description adds that the null can be 3D and positioned but says nothing about defaults, whether a layer is selected afterward, or what the call returns. With annotations doing the heavy lifting, a 3 is appropriate.
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?
A single tight sentence with zero filler, and the core action is front-loaded before the qualifiers. Every clause earns its place.
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 4-parameter creation tool with no output schema, the description is adequate but thin: it does not say what happens when compositionName is omitted, what defaults apply to threeD/position, or what object/identifier is returned. An agent could call it, but with avoidable guesswork.
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 only 25%, with compositionName the sole documented parameter. The description compensates partially by explaining that threeD and position are optional aspects of the null, but it leaves 'name' and the position's coordinate space/units undefined. Some value beyond the schema, but not full compensation for the coverage gap.
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 names a specific verb and resource ('add a null object') and adds a parenthetical explaining the use case (parenting / rigs), which distinguishes it from sibling creators like ae_addSolid or ae_addAdjustment. It does not explicitly compare against those siblings, so it falls short of a 5.
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 parenthetical 'for parenting / rigs' implies when the tool is useful, but there is no explicit guidance on when to prefer a null over a solid or adjustment layer, nor any prerequisites (e.g., which comp the null lands in when compositionName is omitted). Usage is only implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.