Morpha

Set loop

set_loop

Destructive

Set the project's loop section: the whole composition repeats once per value, with one field of one layer varying across the repeats. Builds one pass per value, each setting field of elementId to that value — e.g. a caption text layer cycling through several strings. Pass an empty values array to clear the loop (the comp plays once).

Input Schema

TableJSON Schema

Name	Required	Description
`field`	No	The layer field each pass overrides — e.g. "text", "text_color", "filename". Defaults to "text".
`values`	Yes	One value per loop pass. Empty array clears the loop.
`elementId`	Yes	Target layer — text.<id>, image.<id>, shapes.<id>, or video.<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",
-  "values",
-  "projectId",
-  "anonymousToken"
-]New value: +[
+  "elementId",
+  "values",
+  "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",
-  "values",
-  "projectId"
-]New value: +[
+  "elementId",
+  "values",
+  "projectId",
+  "anonymousToken"
+]

First observedSep 7, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already flag this as a read-write, destructive operation, and the description adds meaningful mechanics: it builds one pass per value, assigns each value to `field` of `elementId`, and notes that an empty array clears the loop state so the composition plays once. This goes beyond the annotations by explaining what the mutation actually does.

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 sentences carry the definition, mechanics, an illustrative example, and the clearing behavior with zero redundancy. The most decision-relevant fact—what a loop pass means—is front-loaded.

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?

For a 4-parameter, 3-required mutation with an output schema, the description fully explains the loop model, how values map to passes, how to clear the loop, and which layer field is affected. No critical operational detail 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 coverage is 100%, so the parameters are already documented with types and examples. The description reinforces the relationship between `values`, `field`, and `elementId` but does not add materially new semantics beyond what the schema provides.

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 opens with a specific verb-resource pair, 'Set the project's loop section,' and immediately defines the behavior: the whole composition repeats once per value while one field of one layer varies. This clearly separates it from sibling tools like set_track_loop, which would target only a track rather than the entire project.

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?

It gives a concrete use case ('a caption text layer cycling through several strings') and explicitly explains how to clear the loop with an empty values array. It does not explicitly name alternatives or list when not to use it, but the project-level scope and example make the intended context clear.

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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