losslesscut-mcp

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Open files

open_files

Opens one or more absolute media or .llc project paths in LosslessCut, loading multiple files into the batch list. Close an already-open file first so LosslessCut does not prompt for a choice.

Instructions

Opens one or more media files (or a .llc project file) in LosslessCut. Paths must be absolute paths the user gave you; never invent or guess paths. Several files are loaded into the batch list. If a file is already open, LosslessCut asks the user what to do, so call close_file first.

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": {
      "paths": "<paths>"
    },
    "name": "open_files"
  }
}

Input Schema

Name	Required	Description	Default
`paths`	Yes	Absolute file paths provided by the user

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Nov 13, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare a non-read-only, non-destructive, closed-world operation. The description adds behavior beyond that: multiple files land in the batch list, a user prompt is triggered for already-open files, and paths must come from the user rather than being guessed. It does not state what happens on a failed load, which is a minor gap.

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?

Three tight sentences with the core action front-loaded, followed by the input constraint and the ordering caveat. No repetition of the title or wasted clauses.

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?

For a one-parameter tool with no output schema, the definition covers action, input provenance, batch semantics, and the close_file prerequisite. Only post-call state (confirmation of what was opened, error behavior on a bad path) is left implicit, which is reasonable given there is no output schema.

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 single paths array is already documented as absolute file paths. The description reinforces and extends this with a sourcing rule ('paths the user gave you; never invent or guess paths') that the schema does not express, which measurably reduces misuse risk.

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 specific verb and resource ('Opens one or more media files ... in LosslessCut') and clarifies the accepted file types, including the .llc project variant. An agent can distinguish it from close_file and export-oriented siblings without opening any schema.

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?

Gives explicit ordering guidance: call close_file first when a file is already open, because LosslessCut will prompt the user. It also constrains inputs to user-supplied absolute paths. It does not describe alternative loading tools or failure handling, but the primary when-to-use condition is stated.

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