MorphaReels

Fit duration to content

fit_duration_to_content

Destructive

Clear an authored composition length and return to AUTO-FIT — the comp length tracks the furthest content (keyframe / video window / audio end) again, with a 1-second floor. The inverse of set_duration. NOTE: headless (no loaded media) this can UNDER-fit when a video layer's source_out_frame is null — its natural length is unmeasurable, so it contributes only its start frame; the length self-corrects the next time the project is opened in the editor, where the real clip durations are known.

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": {
      "projectId": "<projectId>"
    },
    "name": "fit_duration_to_content"
  }
}

Input Schema

Name	Required	Description	Default
`projectId`	Yes	Opaque project id (a v4 UUID, from list_projects/create_project). Selects which existing project this call mutates.

Output 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: -[
-  "projectId",
-  "anonymousToken"
-]New value: +[
+  "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: -[
-  "projectId"
-]New value: +[
+  "projectId",
+  "anonymousToken"
+]

First observedSep 7, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Beyond the annotations (readOnlyHint false, destructiveHint true), the description discloses the destructive clearing action, the auto-fit behavior, the 1-second floor, and a significant edge case where it can under-fit in headless mode and later self-correct. This adds valuable behavioral context not present in the annotations.

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

Conciseness4/5

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

The description is efficient and front-loaded with the core purpose. The note about headless under-fitting is long but necessary and clearly separated. Overall it is well-structured without unnecessary filler.

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 covers the primary behavior, the inverse relationship with set_duration, and a critical edge case that affects correctness. Since an output schema exists, return value details are not required. For a single-parameter mutation tool, this is complete and actionable.

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?

The schema already provides a thorough description of projectId (opaque v4 UUID, from list_projects/create_project, selects project to mutate). The tool description does not add any additional parameter details, but with 100% schema coverage, the baseline is 3. No extra value is needed.

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 clearly states the action: 'Clear an authored composition length and return to AUTO-FIT', specifying the resource (composition length) and the behavior (tracks furthest content with a 1-second floor). It also identifies itself as the inverse of set_duration, which distinguishes it from sibling tools like set_duration.

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 names set_duration as the inverse, providing a clear alternative and implying when to use this tool (to revert to auto-fit). It also gives a specific condition (headless with null source_out_frame) where under-fitting may occur, helping the agent decide when to invoke it and what to expect.

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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