Morpha

Set layer block

set_layer_block

Destructive

Set (or replace) a layer's timeline BLOCK — the [start, start+duration) window it exists for. The layer is drawn ONLY inside that window, and its animation keyframes are sampled RELATIVE to the block start, so moving or trimming the block re-anchors its intro instead of leaving it behind. This is how a layer 'starts' at a point like an iMovie clip rather than being present for the whole composition. Works on any leaf or group. Frames are in the layer's parent timeline (composition frames at root; band-local inside an embedded morpha band). To place a whole embedded reel, use move_band.

Input Schema

TableJSON Schema

Name	Required	Description
`start`	Yes	First frame the layer appears (0-indexed, 30 fps), in its parent timeline.
`duration`	Yes	How many frames the layer lasts (≥ 1). Hidden outside [start, start+duration).
`elementId`	Yes	Element id of the layer (image.<id>, video.<id>, text.<id>, shapes.<id>, or group.<id>).
`projectId`	Yes	Opaque project id (a v4 UUID, from list_projects/create_project). Selects which existing project this call mutates.

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	Yes	Whether the call succeeded.
`data`	No	The payload, shaped by the tool.
`note`	No	What to do next when not ready.
`error`	No	Why it failed.
`status`	No	For cache-backed readers: whether the answer was ready.
`editorUrl`	No	Opens this project in the editor.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 17, 2026

removedInput schema / properties / anonymousToken

Removed value: -{
-  "description": "The token create_anonymous_account returned. This connection has no Morpha key, so every call carries it.",
-  "type": "string"
-}

changedInput schema / required

Previous value: -[
-  "elementId",
-  "start",
-  "duration",
-  "projectId",
-  "anonymousToken"
-]New value: +[
+  "elementId",
+  "start",
+  "duration",
+  "projectId"
+]

Changed1 schema field changedSep 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "description": "The result envelope every Morpha tool returns.",
+  "properties": {
+    "data": {
+      "description": "The payload, shaped by the tool.",
+      "type": [
+        "object",
+        "array",
+        "string",
+        "number",
+        "boolean",
+        "null"
+      ]
+    },
+    "editorUrl": {
+      "description": "Opens this project in the editor.",
+      "type": "string"
+    },
+    "error": {
+      "description": "Why it failed.",
+      "type": "string"
+    },
+    "note": {
+      "description": "What to do next when not ready.",
+      "type": "string"
+    },
+    "ok": {
+      "description": "Whether the call succeeded.",
+      "type": "boolean"
+    },
+    "status": {
+      "description": "For cache-backed readers: whether the answer was ready.",
+      "enum": [
+        "ready",
+        "not-ready"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "ok"
+  ],
+  "type": "object"
+}

Changed2 schema fields changedSep 11, 2026

addedInput schema / properties / anonymousToken

Added value: +{
+  "description": "The token create_anonymous_account returned. This connection has no Morpha key, so every call carries it.",
+  "type": "string"
+}

changedInput schema / required

Previous value: -[
-  "elementId",
-  "start",
-  "duration",
-  "projectId"
-]New value: +[
+  "elementId",
+  "start",
+  "duration",
+  "projectId",
+  "anonymousToken"
+]

First observedSep 7, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation risk is known. The description adds valuable behavioral context: the layer is drawn ONLY inside the window, keyframes are sampled RELATIVE to the block start, and moving/trimming re-anchors the intro. It also clarifies frame coordinate context (parent timeline, band-local inside embedded morpha band). It doesn't explicitly state that replacing an existing block destroys the old one, but the 'replace' wording plus destructiveHint covers that.

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?

The description is compact and front-loaded: the core definition and window semantics come first, followed by the keyframe re-anchoring behavior, then the use-case analogy, then frame coordinate context, and finally the sibling alternative. Every sentence earns its place and no filler exists.

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

Completeness5/5

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

The description is complete for a mutation tool with a full schema and output schema. It covers what the block is, how it behaves, what coordinate system frames use, and which sibling to use instead for embedded reels. The destructive nature is already in annotations, and the output schema handles return values, so nothing critical 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 four parameters. The description adds meaning by explaining the semantic relationship between start and duration (the [start, start+duration) window) and the relative keyframe sampling, which goes beyond the schema's individual parameter descriptions. However, it doesn't add new per-parameter details beyond what the schema provides, so a baseline 3 is appropriate.

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

Purpose5/5

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

The description states a specific verb ('Set (or replace)'), a precise resource ('a layer's timeline BLOCK'), and defines the block as '[start, start+duration) window'. It distinguishes this from simply adding a layer and from move_band, so an agent can tell it apart from siblings without opening the schema.

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

Usage Guidelines5/5

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

The description explicitly explains when to use this tool: to make a layer 'start' at a point like an iMovie clip rather than being present for the whole composition. It also names the alternative for placing a whole embedded reel ('use move_band'), giving clear routing guidance.

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

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