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Edit a video from a description

edit_video

Change what a video shows from a written instruction. The new video keeps the clip's motion, camera, timing and sound, and changes only what you name: a colour ("make her shorts red"), clothes ("turn his shirt into a black hoodie"), an object added, removed or swapped, the background, the weather, the time of day or the season, or the whole look (anime, clay, film noir). With references it puts what the pictures show into the video: a face, an outfit, a product, a logo or a place. Load builtin-generative-video first: it has the prompt rules and says when to use replace_person or copy_motion instead. It edits 3 to 10 seconds of video: a video asset, a part of one (startSeconds and endSeconds), or a group of the film (group), whose clips it edits together as one picture. The new video is as long as what it edited: for a whole asset, play it with the clip's at, offset and duration; for a part, it starts at startSeconds, so play it at offset 0 where that part played; for a group, put it in the group in place of its tracks, at 0, so the group's look and transitions still apply. It answers at once with a Job ID and the media is made in the background: start every generation you need, keep working, then call wait_for_jobs with all their Job IDs to get each Asset ID for patch_film. Uses credits for each second of the clip: about 38 credits a second, or about 48 credits a second with references, so a 5-second clip uses 190 credits, or 239 with references.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
groupYesThe id of a <group> in the film to edit as one video, instead of an asset: everything it holds (its cuts, titles and overlays) is drawn together, without the group's own look, and edited as one picture. The group is 3 to 10 seconds long. null with videoAssetId.
promptYesThe change, in one or two plain sentences that name what changes and end with "Keep everything else the same.": "Make her white shorts bright red. Keep everything else the same." With references, call the video @Video1 and the pictures @Image1 to @Image4 by their order: "Replace the face of the man in @Video1 with the face in @Image1. Keep his hair, clothes and everything else the same." Up to 2000 characters.
projectIdYesThe project this call runs on without changing the open project. null (or leaving it out) uses the open project. wait_for_jobs takes the projectId of the calls that started the jobs.
endSecondsYesSource second of videoAssetId where the part to edit ends; null for both edits the whole video.
referencesYes1 to 4 pictures of what to put in (a face, an outfit, a product, a logo, a place), in this order, each in one of these forms: asset:ID, an image asset as it is; asset:ID#t=14.6, the frame of a video asset at 14.6 seconds; film:#t=3.2, the frame of the edit at 3.2 seconds. Use the IDs search_assets gives. null when the description says it all.
startSecondsYesSource second of videoAssetId where the part to edit starts, with endSeconds; null for both edits the whole video. Pass the part a clip plays (its offset to offset + duration) instead of importing that part first.
videoAssetIdYesThe video to edit: a ready video asset. What is edited (the whole video, or startSeconds to endSeconds of it) is 3 to 10 seconds, with references at least 720 pixels on each side. Use the IDs search_assets gives. null with group.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

A4.8/5.0
Behavior5/5

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

Annotations declare non-readOnly, openWorld, non-idempotent, non-destructive, but the description adds the operationally critical facts: it returns a Job ID immediately and renders in the background, requires wait_for_jobs plus patch_film afterwards, and costs ~38 credits/sec (~48 with references). The output-length and playback-placement behaviour (at/offset/duration, offset 0 for a part, in-group placement) is disclosed as well.

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?

Purpose and the edit taxonomy are front-loaded before routing, cost and timing details. It is dense and some sentences chain many clauses (the playback-placement sentence), but almost every sentence carries decision-relevant information rather than filler.

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, expensive async generation tool with no output schema, the description covers the return shape (Job ID, then Asset ID via wait_for_jobs), follow-up tooling, cost, duration limits and placement semantics. Nothing an agent needs before calling it 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 coverage is 100%, so the baseline is 3, but the description adds genuine meaning beyond the schema: prompt phrasing conventions, how references map to @Video1/@Image1-4, and how the resulting clip must be placed back into the timeline. Some material (3-10s limit, 720px, reference string forms) is duplicated from the schema, so it does not fully escape the baseline.

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?

States a concrete verb+resource (change what a video shows from a written instruction) and enumerates exactly what can be changed: colour, clothes, objects, background, weather, time of day, season, whole look. It distinguishes itself from siblings by naming replace_person and copy_motion as the tools to use for other kinds of edits.

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

Usage Guidelines5/5

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

Explicitly says to load builtin-generative-video first for prompt rules and for when to use replace_person or copy_motion instead. It also gives the selection logic between whole-asset, startSeconds/endSeconds part, and group editing, and specifies 3-10 second bounds, so the agent knows exactly when this tool applies.

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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