Premiere Pro MCP Server

Build Caption Artifact

build_caption_artifact

Creates SRT/VTT captions from word timelines with balanced cues, sentence breaks, karaoke timestamps, emphasis, and speaker labels. Returns inline or writes to approved workspace; Premiere unchanged.

Instructions

Build a CapCut/Submagic-style SRT or VTT caption artifact from a caller-supplied word timeline: balanced word groups, sentence-aware breaks, min/max cue durations, optional karaoke word timestamps (VTT), emphasis and speaker markup. Local-only; returns the artifact inline or writes it inside an approved workspace and never changes Premiere.

Input Schema

TableJSON Schema

Name	Required	Description
`format`	Yes	Artifact format. SRT uses HH:MM:SS,mmm; VTT starts with WEBVTT and uses HH:MM:SS.mmm.
`karaoke`	No	VTT only: emit per-word <HH:MM:SS.mmm> timestamps inside each cue for word-highlight styles. Errors for SRT.
`max_lines`	No	Maximum lines of plain caption text per cue (default 1); markup does not add lines.
`uppercase`	No	Render caption text in upper case.
`output_path`	No	Optional absolute file path to write the artifact to. Requires approved_workspace_path; the file must not already exist. When omitted the artifact text is returned inline (up to 512 KiB).
`style_preset`	No	Style descriptor to return with the artifact (default clean). Documentation only; not encoded in SRT/VTT.
`strip_fillers`	No	Tokens removed from the caption text (case-insensitive, punctuation ignored).
`word_timeline`	Yes	Caller-supplied word-timed transcript for one Premiere source item. Words must be ordered by start time and bound to the transcript revision returned by get_clip_transcript_uxp.
`words_per_cue`	No	Target words per cue (default 4); sentences are split into balanced groups of at most this many words.
`emphasis_words`	No	Words wrapped in <b> (SRT) or <c.emphasis> (VTT).
`speaker_prefix`	No	Prefix cues with the speaker label when present: 'Speaker: ' in SRT, <v Speaker> in VTT.
`max_cue_seconds`	No	Maximum cue duration (default 5).
`min_cue_seconds`	No	Minimum cue duration (default 0.5); short cues are extended but never past the next cue start.
`merge_gap_seconds`	No	Extend a cue to the next cue start when the gap is smaller than this (default 0.3) so captions do not flicker.
`max_chars_per_line`	No	Maximum characters per line of plain caption text (default 32); words are never split. Wrapping counts unescaped words only, so VTT escaping, karaoke timestamps, emphasis tags, and speaker prefixes can make the rendered line longer.
`approved_workspace_path`	No	Absolute existing directory that must contain output_path (checked via realpath of the parent directory). Required with output_path.

Output Schema

TableJSON Schema

Name	Required	Description
`ok`	Yes	Whether the tool completed successfully.
`data`	No	Tool-specific result data when ok is true.
`tool`	Yes	The registered MCP tool name.
`error`	No	Failure detail when ok is false.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.14.9Sep 8, 2026

TDQS

A4.5/5.0

Behavior5/5

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

Beyond the sparse annotations, the description discloses local-only execution, the two return modes (inline artifact or file write inside an approved workspace), and the hard guarantee that Premiere is never changed. This gives an agent critical side-effect and safety information.

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?

Two dense sentences front-load the core purpose and the most important behavioral constraints. Every clause contributes information; there is no filler or repetition of schema content.

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?

For a complex 16-parameter tool with a rich schema and an output schema, the description covers the critical context: input source, output format, side effects, and the Premiere safety boundary. Remaining details live in the schema, which is appropriate given the schema's thoroughness.

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 input schema already documents all 16 parameters with 100% coverage, so the baseline applies. The description adds a useful high-level summary of the grouping algorithm and optional markup, but it does not introduce new parameter-level constraints or relationships beyond what the schema provides.

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 ('Build'), a precise resource ('SRT or VTT caption artifact'), and the input ('caller-supplied word timeline'). It also distinguishes itself from caption-track editing siblings by stating it is local-only and never changes Premiere.

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?

It gives clear context: use this when you need a standalone SRT/VTT artifact from a word timeline, and it explicitly excludes Premiere mutation. However, it does not name alternative tools such as create_caption_track or read_sequence_captions, nor give explicit when-not conditions, so the guidance is implied rather than fully explicit.

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

Deploy Server