MorphaReels

Add audio overlay

add_audio_overlay

Add an audio overlay (mp3/m4a/wav/ogg) scheduled at a frame-aligned start. The asset must already be uploaded (upload_audio, or the editor for a file from the person's disk); pass the upload's returned filename, and its name as the track's label. 30 fps; convert seconds with frames = round(s * 30). Plays in the editor preview and is mixed into the MP4 export.

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": {
      "filename": "<filename>",
      "startFrame": "<startFrame>",
      "projectId": "<projectId>"
    },
    "name": "add_audio_overlay"
  }
}

Input Schema

Name	Required	Description
`gain`	No	Linear gain 0..2. Default 1.
`name`	No	Optional label people see on the track: pass the upload's returned `name`.
`endFrame`	No	Optional end frame; omit to play the asset's full natural length from startFrame.
`filename`	Yes	The stored audio filename an upload returned.
`projectId`	Yes	Opaque project id (a v4 UUID, from list_projects/create_project). Selects which existing project this call mutates.
`startFrame`	Yes	Frame at which the overlay starts (0-indexed, 30 fps).
`fadeInFrames`	No	Linear fade-in length in frames. Default 0.
`fadeOutFrames`	No	Linear fade-out length in frames. Default 0.
`sourceLayerId`	No	Optional video layer element id ("video.<id>") to weld this overlay to. When set, the editor renders the overlay as a waveform footer on that clip and drags it with the clip instead of showing a standalone bottom row.

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

changedInput schema / properties / filename / description

Previous value: -"Audio asset filename in the project's assets bucket."New value: +"The stored audio filename an upload returned."

addedInput schema / properties / name

Added value: +{
+  "description": "Optional label people see on the track: pass the upload's returned `name`.",
+  "type": "string"
+}

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: -[
-  "filename",
-  "startFrame",
-  "projectId",
-  "anonymousToken"
-]New value: +[
+  "filename",
+  "startFrame",
+  "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: -[
-  "filename",
-  "startFrame",
-  "projectId"
-]New value: +[
+  "filename",
+  "startFrame",
+  "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?

With readOnlyHint=false and destructiveHint=false already declared, the description sensibly focuses on effect rather than safety: the overlay "Plays in the editor preview and is mixed into the MP4 export," which tells the agent where the change surfaces. It does not cover failure modes (e.g., bad filename, overlapping overlays), but output schema covers the response shape.

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?

Four dense sentences, front-loaded with purpose first and prerequisites second, with no filler. The only mild redundancy is restating the upload's `filename`/`name` binding that the schema also documents.

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 9-parameter mutation tool with an output schema and annotations, the description supplies the important missing context: accepted formats, the upload prerequisite, the fps math, and the ultimate effect on preview/export. Minor gaps remain around error behavior and how this interacts with an existing overlay on the same track.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description earns above baseline by supplying the conversion rule "frames = round(s * 30)" at 30 fps and tying `filename`/`name` to the upload's returned values, which directs how to populate required and optional fields. The remaining params (gain, fades, sourceLayerId) are documented adequately in the schema itself.

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?

Opens with a specific verb + resource ("Add an audio overlay") and enumerates accepted formats (mp3/m4a/wav/ogg), plus the frame-aligned scheduling constraint. It also names the sibling that must run first (upload_audio), so an agent can place this tool in the workflow without opening a schema.

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?

States a clear prerequisite ("The asset must already be uploaded") and points to upload_audio as the alternative entry point, plus how to derive the label from the upload's returned `name`. It stops short of naming update_audio_overlay/remove_audio_overlay as the alternatives for editing or deleting an existing overlay, so the when-not case is left implicit.

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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