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ae_set_property

Set any layer or effect property by path in After Effects; include a time to create a keyframe or omit it for static values, in one undo step.

Instructions

Set any property of a layer or of its effects by path. With time, sets a keyframe; without time the property must have no keyframes. One undo step.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "layer": "<layer>",
      "property": "<property>",
      "value": "<value>"
    },
    "name": "ae_set_property"
  }
}

Input Schema

Name	Required	Description
`comp`	No	Composition name or numeric item id. Omit to use the active composition.
`time`	No	Time in seconds (composition time).
`layer`	Yes	Layer name or 1-based index.
`value`	Yes	Number, array, color ('#RRGGBB' for color properties), text or text-style object for Source Text.
`property`	Yes	Property path: 'Transform/Position', 'Opacity', 'Source Text', 'Effects/Gaussian Blur/Blurriness' (names, matchNames or 1-based indices, '/'-separated or as an array).

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Oct 17, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It usefully discloses the keyframe-vs-static constraint and that the call is 'One undo step,' which is real behavioral context. It omits error behavior, permission/active-composition requirements, and what happens on a type mismatch.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with the core action and followed by the two most decision-relevant constraints (keyframe rule, undo behavior). Every sentence earns its place with no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a mutation tool with no annotations, no output schema, and full parameter documentation, the description covers the essential behavioral traits an agent needs: path targeting, keyframe semantics, and undo granularity. Only error/edge-case handling is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all five parameters thoroughly (comp, time, layer, value, property). The description adds only the 'by path' framing and ties time to keyframe creation, so baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource: 'Set any property of a layer or of its effects by path,' which clearly conveys the operation. It does not, however, explicitly disambiguate from siblings like ae_set_keyframes or ae_set_expression, leaving the boundary to be inferred.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives a concrete usage condition: 'With time, sets a keyframe; without time the property must have no keyframes.' This tells the agent when each mode applies. It stops short of naming alternative tools (e.g. ae_set_keyframes) for the keyframe workflow.

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