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ff-toolkit

ff-toolkit

by inthepond
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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ffkit_merge

Concatenate multiple media files into one file. Choose the fast concat_demuxer for same-codec files or the cross-format concat_filter for re-encoding.

Instructions

Concatenate multiple media files into one. Use concat_demuxer (fast, same codec) or concat_filter (re-encodes, cross-format).

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>",
      "output_path": "<output_path>"
    },
    "name": "ffkit_merge"
  }
}

Input Schema

NameRequiredDescriptionDefault
methodNoMerge strategy. Default: concat_demuxer.
input_pathsYesOrdered list of file paths to concatenate.
output_pathYesDestination path for the merged file.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.4/5.0
Behavior4/5

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

Without annotations, the description fully carries the burden of behavioral disclosure. It states that the tool concatenates media files, explains two merge strategies (fast vs re-encodes), and implies the output is a single file. This is clear and sufficient for a straightforward tool with no destructive or auth concerns. No contradictions exist.

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, zero wasted words. Each sentence earns its place: the first states the purpose, the second gives usage guidance. The structure is front-loaded with the action first, followed by method-specific details.

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?

Given no output schema and simple parameters, the description adequately covers what the tool does and how to choose the method. It could be slightly more complete by mentioning the file format requirement for concat_demuxer (same codec), but the 'same codec' hint suffices. No critical gaps remain.

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 schema already describes each parameter. The description adds value by explaining the trade-off between concat_demuxer (fast, same codec) and concat_filter (re-encodes, cross-format) – critical semantic context beyond the schema's enum labels. Input_paths and output_path are self-explanatory, so no extra detail needed.

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 uses a specific verb ('Concatenate') and resource ('multiple media files') that clearly states the tool's function. It also distinguishes between two methods (concat_demuxer vs concat_filter), adding precision. Among sibling tools like ffkit_clip or ffkit_extract_audio, this description uniquely identifies merging behavior.

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 provides explicit guidance on when to use each method (same codec vs cross-format), which helps the agent choose correctly. However, it does not mention when not to use this tool versus alternatives like ffkit_clip or ffkit_transcode for related tasks (e.g., trimming or conversion).

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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