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Glama

Morpha

by ai.morphareels

add_caption_track

Build a caption track from pre-timed lines (e.g. derived from transcribe_clip's word timings). mode "line-sync" (default) creates one text layer per line, each shown only during its [startFrame, endFrame) window via hold-eased opacity keyframes — the active-line karaoke read; mode "static" makes a single layer with all lines joined. style picks a preset look. Lines default to a lower-third band. The caption layers are always wrapped in a "captions" group so they don't clutter the layers list. Returns the created text element ids plus groupElementId (the captions group).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
xNoCaption band centre x. Default canvas centre.
yNoCaption band centre y. Default lower third (~80% of height).
modeNo"line-sync" (default): one timed layer per line. "static": one layer with all lines.
linesYesCaption lines in order. Each: { text, startFrame, endFrame } — frames are 0-indexed at 30fps.
styleNoCaption look preset. Default "classic".
widthNoBand width. Default ~86% of canvas width.
heightNoBand height. Default ~16% of canvas height.
projectIdYesOpaque project id (a v4 UUID, from list_projects/create_project). Selects which existing project this call mutates.
clip_element_idNoOptional "video.<id>" to WELD the caption lines to (line-sync mode). When set, each line's startFrame/endFrame are treated as its window in the clip's OWN source timeline and the on-timeline position is derived live from the clip's trim — so trimming or sliding the clip retimes/clips the captions, exactly like the clip's welded audio. Omit for fixed project-frame captions.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observed

TDQS

A4.7/5.0
Behavior5/5

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

With no annotations available, the description carries the full burden and does so richly: it discloses the two modes, how line-sync visibility windows work via hold-eased opacity keyframes, that layers are always wrapped in a 'captions' group, and what the call returns. This is exemplary transparency for a creation tool.

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?

The description is dense but every sentence earns its place: purpose, mode behavior, style, default placement, grouping behavior, and return value. It front-loads the most important information and avoids filler or repetition.

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?

Given the lack of annotations and output schema, the description supplies the essential behavioral and return context: created text element ids plus groupElementId, the grouping guarantee, and the two modes. The comprehensive input schema covers parameters, so nothing critical for calling this tool correctly is missing.

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 description coverage is 100%, so the baseline is 3. The description goes beyond the schema by explaining how mode line-sync behaves ('active-line karaoke read'), what the group wrapping means for the layer list, and that the return includes groupElementId. This adds real semantic value on top of the complete schema.

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 plus resource: 'Build a caption track from pre-timed lines.' It distinguishes this from related siblings like transcribe_clip (which produces timings) and merge_caption_lines/split_caption_line (which manipulate existing caption lines), while the mode detail further clarifies exactly what is built.

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?

The description clearly signals when to use this tool: after obtaining pre-timed lines, e.g. from transcribe_clip's word timings. It gives clear context but does not explicitly contrast it with merge_caption_lines or split_caption_line, so it lacks explicit when-not-to-use guidance.

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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TDQS

A3.6/5.0
Disambiguation3/5

The tool set has several clusters that overlap conceptually: add_keyframe/add_keyframes/set_keyframes_batch, move_band/move_layer/shift_group/set_group_window, and fade_layer/set_layer_transition/set_layer_visible all target similar actions. However, each tool's description is distinct and detailed enough for an agent to disambiguate after careful reading. The sheer volume of 95 tools still creates meaningful selection risk.

Naming Consistency4/5

Tool names overwhelmingly follow a verb_noun snake_case pattern (add_, remove_, set_, list_, rename_, create_, delete_), which is predictable and readable. Minor inconsistencies exist: plural variants like add_keyframes vs add_keyframe, mixed specificity like remove_keyframe vs remove_color_keyframe, and a few oddballs like reid_project and clip_processing_status. Overall the pattern is strong and helps navigation.

Tool Count2/5

95 tools is far beyond the well-scoped range and will overwhelm agents; even a comprehensive video editor could consolidate keyframe batch operations, overlay/track manipulations, and page/group window controls. Many tools are highly specific (reid_project, safe_zones, move_band) and place burden on the agent to pick among near-synonym verbs. While the broad domain justifies many operations, this count is excessive for a coherent tool surface.

Completeness3/5

The surface covers a broad editing lifecycle: layers, keyframes, text, captions, audio, pages, groups, versions, projects, workspaces, and collections, including batch operations. However, there is no MCP tool to render/export the final MP4 (explicitly delegated to an SDK) and no upload_video tool for bringing in a clip file, leaving major end-to-end gaps. For the stated purpose of building and editing videos, these are significant omissions that force agents to stop short of delivery.

Resources