Valmera — AI Video Editor

Add captions

add_captions

Creates burned-in captions from the word-timed transcript or explicitly supplied text items with source timestamps, or disables captions. Styling supports named presets and detailed presentation parameters.

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": {
      "project_id": "<project_id>"
    },
    "name": "add_captions"
  }
}

Input Schema

Name	Required	Description
`mode`	No
`items`	No
`style`	No
`project_id`	Yes	Explicit project identifier for this request. The connection's navigation pointer does not select the target.
`motion_motif`	No	Active Blueprint motion motif id this event executes; never 'hold'.
`emphasis_words`	No
`max_words_per_caption`	No
`min_words_per_caption`	No	Preferred minimum for static phrase presets such as clean; QA flags unavoidable fragments.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedNov 14, 2026
- removedInput schema / properties / style / properties / anchor_x
```
Removed value: -{
-  "maximum": 1,
-  "minimum": 0,
-  "type": "number"
-}
```
Changed1 schema field changedNov 14, 2026
- addedInput schema / properties / style / properties / anchor_x
```
Added value: +{
+  "maximum": 1,
+  "minimum": 0,
+  "type": "number"
+}
```

Changed1 schema field changedNov 6, 2026

changedInput schema / properties / project_id / description

Previous value: -"Required immutable scope for this call. Copy the id from list_projects/open_project/project_state; the active-project pointer is never used to guess."New value: +"Explicit project identifier for this request. The connection's navigation pointer does not select the target."

Changed3 schema fields changedOct 9, 2026

addedInput schema / properties / style / properties / leading / maximum
```
Added value: +2.2
```
addedInput schema / properties / style / properties / leading / minimum
```
Added value: +0.5
```

addedInput schema / properties / style / properties / motion_look

Added value: +{
+  "description": "Browser-drawn caption look, the default for short-form/podcast/premium: editorial = bold sans + big serif-italic emphasis word, hard pops; clean = calm sentence case rising from a blur; lockup = small caps over one huge hero word; pop = outlined hype punches; box = gliding highlight pill; serif = gold serif-italic emphasis; glow = karaoke; stack = giant condensed hero; mono = typewriter. null = presets.",
+  "enum": [
+    "editorial",
+    "clean",
+    "lockup",
+    "pop",
+    "box",
+    "serif",
+    "glow",
+    "stack",
+    "mono"
+  ],
+  "type": "string"
+}

Changed1 schema field changedOct 5, 2026

changedInput schema / properties / style / properties / preset / enum

Previous value: -[
-  "clean",
-  "documentary",
-  "broadcast",
-  "retro",
-  "neon",
-  "podcast",
-  "reels",
-  "beast",
-  "karaoke",
-  "elegant",
-  "spotlight",
-  "stacked",
-  "iridescent",
-  "chrome",
-  "editorial",
-  "fashion",
-  "luxe",
-  "impact",
-  "lyric",
-  "classic"
-]New value: +[
+  "composed",
+  "clean",
+  "documentary",
+  "broadcast",
+  "retro",
+  "neon",
+  "podcast",
+  "reels",
+  "beast",
+  "karaoke",
+  "elegant",
+  "spotlight",
+  "stacked",
+  "iridescent",
+  "chrome",
+  "editorial",
+  "fashion",
+  "luxe",
+  "impact",
+  "lyric",
+  "classic"
+]

First observedSep 9, 2026

TDQS

B3.1/5.0

Behavior3/5

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

Annotations already establish that this is a mutation, not read-only, non-idempotent, and not marked destructive. The description adds that captions are burned-in and can be sourced from transcript timing or explicit items, but it does not explain replacement behavior, mode semantics, or what happens to existing captions.

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 two tightly written sentences and front-loads the main action and caption source options. The second sentence is slightly vague about what 'detailed presentation parameters' includes, but there is little wasted wording.

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

Completeness2/5

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

This is a complex mutation tool with eight top-level parameters, a large nested style object, low schema description coverage, and no output schema. The description identifies the core behavior but is too thin to explain modes, item structure, styling controls, or operational effects.

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

Parameters2/5

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

Schema description coverage is low at 38%, so the description must compensate, but it only vaguely maps the items and style parameters. It says nothing useful about mode, emphasis_words, max_words_per_caption, or most of the nested style fields, leaving significant gaps.

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 description states a specific verb and resource: creates burned-in captions from a word-timed transcript or supplied text items, or disables captions. It is clear about what the tool does, but it does not explicitly distinguish this from caption-related siblings such as set_caption_style or audit_captions.

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?

The description implies when the tool is used by naming valid caption sources and the ability to disable captions, but it does not explicitly say when to choose this over set_caption_style or when to audit captions instead. Usage guidance is present but mostly inferential.

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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