ffmpeg-mcp-video-editor

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Concatenate clips

concat

Combine two or more clips into one file, preserving quality when codecs, resolution, and frame rate match, or automatically normalizing and re-encoding mismatched clips.

Instructions

Join two or more clips end to end into a single file.

When every clip already shares a codec, resolution and frame rate, this remuxes with no re-encoding. Otherwise the clips are normalised first — scaled and padded to a common resolution, resampled to a common frame rate and audio layout — and then concatenated, which requires a re-encode.

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": {
      "input_paths": "<input_paths>"
    },
    "name": "concat"
  }
}

Input Schema

Name	Required	Description
`encode`	No
`target_fps`	No	Force a common frame rate.
`input_paths`	Yes	Clips to join, in order.
`output_path`	No	Destination file; defaults to the job workspace.
`target_resolution`	No	Force all clips to this size, e.g. '1920x1080'. Defaults to the first clip's resolution when the clips differ.

Output Schema

Name	Required	Default
`tool`	Yes
`job_id`	Yes
`status`	No	queued
`message`	No	Job queued. Poll job_status for progress, then job_result.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 6, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With annotations being minimal (all false hints), the description carries the burden and does well by detailing normalization steps (scaling, padding, resampling, audio layout) and the re-encode requirement. This goes beyond what the structured annotations reveal.

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 sentences with no filler. The core action is front-loaded, and the second sentence precisely explains the conditional behavior. Every phrase contributes value.

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

Completeness4/5

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

The tool has a nested encode object plus an output schema, and the description covers the main workflow and edge cases (compatible vs incompatible clips). It does not specify input media types, but the schema and output schema mitigate that gap.

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 80%, so the burden on the description is low. The description adds context about normalization behavior that relates to target_resolution and target_fps, but most parameter meaning is already present in the 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 'Join two or more clips end to end into a single file,' which is a specific verb+resource statement that clearly distinguishes this tool from siblings like overlay_media or trim. It unambiguously communicates the core function.

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 explains when remuxing happens (compatible clips) and when re-encoding occurs (incompatible clips), giving the agent context for expected behavior. It does not explicitly name alternatives or exclusions, but the conditions are clear enough to guide usage.

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