opentoonz-mcp

Overview Schema Source Related Servers Discussions Admin

Opentoonz Render Video

opentoonz_render_video

Render a scene to an MP4 video by muxing frames with ffmpeg, optionally adding AAC audio, and setting CRF/scale for quality and size.

Instructions

Render a scene and mux the frames into an MP4 with ffmpeg.

audio (optional) is a path to an external soundtrack (mp3, wav, ...). It is encoded as AAC and cut to the video's length. OpenToonz's own audio columns cannot be reached from the scripting API, so audio always comes from a file. crf (0-51, lower is better) trades quality for file size, and scale (a positive factor, e.g. 0.5) resizes the video.

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": {
      "workspace": "<workspace>",
      "scene": "<scene>"
    },
    "name": "opentoonz_render_video"
  }
}

Input Schema

Name	Required	Default
`crf`	No
`fps`	No
`audio`	No
`scale`	No
`scene`	Yes
`out_name`	No	video
`workspace`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.8.0Oct 17, 2026

TDQS

B3.4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden and does add real value: it discloses that audio always comes from an external file because OpenToonz audio columns are unreachable via the scripting API, that audio is AAC-encoded and truncated to video length, and the crf/scale tradeoffs. It still omits key operational behavior for a file-producing tool: output location, whether an existing file is overwritten, failure modes, and roughly how long/synchronous the render is.

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 front-loaded with the core action and then devotes short, purposeful sentences to each optional parameter. The aside about OpenToonz audio columns is slightly discursive but justifies a non-obvious constraint, so most sentences earn their place.

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

Completeness3/5

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

For a 7-parameter, no-annotation, no-output-schema tool that writes a file, the description covers the video-specific knobs but leaves the required identifiers (workspace, scene), output naming/location, fps, and overwrite behavior to the bare schema. It is adequate to start a call but not to predict the result confidently.

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 0%, so the description must compensate, and it explains 3 of 7 parameters well (audio source format, crf range 0-51 and direction, scale as a positive factor). The required workspace and scene parameters, plus out_name and fps (default 24), get no semantic explanation at all, leaving nearly half the surface undocumented.

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?

The first sentence names a specific verb (render), resource (scene), and concrete output (MP4 muxed with ffmpeg), so the agent knows exactly what the tool produces. However, it never explicitly distinguishes itself from the many render siblings (opentoonz_render, opentoonz_render_gif, opentoonz_render_batch, opentoonz_render_frame), which the agent must infer from the format keyword 'MP4'.

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

Usage Guidelines3/5

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

Usage is only implied: the MP4/ffmpeg framing suggests 'use this when you want a video file', but there is no statement of when to prefer it over opentoonz_render or opentoonz_render_gif, nor any prerequisites such as the scene needing to exist or renders needing prior setup. No exclusions or alternatives are named.

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