vlc-mcp

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set_sync_delay

Adjust audio or subtitle delay in VLC to correct out-of-sync playback; use negative, fractional, or zero seconds to align timing.

Instructions

Set the audio or subtitle delay to fix out-of-sync playback.

Args: stream: "audio" or "subtitle" seconds: Delay in seconds (can be negative or fractional, e.g. -0.5). 0 resets it.

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": {
      "stream": "<stream>",
      "seconds": "<seconds>"
    },
    "name": "set_sync_delay"
  }
}

Input Schema

Name	Required	Description	Default
`stream`	Yes
`seconds`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

A3.9/5.0

Behavior3/5

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

No annotations are supplied, so the description carries the full burden; it does disclose that 0 resets the delay and that negative/fractional values are valid, which is useful behavioral detail. It omits whether the setting applies only to the current playback session or persists across tracks, and whether it requires an active player state.

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?

One leading sentence states purpose and intent, followed by a compact Args block for the two parameters. No filler, and the most important information is front-loaded.

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?

An output schema exists, so the description need not explain return values, and it adequately covers both required parameters. The remaining gap is scope/persistence of the delay setting, which matters for a two-parameter mutation on a live player.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0% and the schema types are bare, yet the description supplies the accepted values for stream ("audio" or "subtitle" — effectively an enum missing from the schema) and fully explains seconds including sign, fractional values, and the 0 reset sentinel. This adds substantial meaning beyond the input schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb (set) plus resource (audio or subtitle delay) and the motivating goal (fix out-of-sync playback), which lets an agent separate it from siblings like set_playback_rate or set_volume. It does not explicitly name any sibling, so it stops short of a 5.

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

Usage Guidelines3/5

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

Usage is implied by 'fix out-of-sync playback', which gives a clear trigger condition. There is no statement of when not to use it, no mention of prerequisites (e.g. a media item must be playing), and no comparison to the more general vlc_control sibling.

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