suprsonic-mcp

subtitle

Create SRT or VTT caption files from audio or video URLs. Select format and language to generate text tracks for accessibility and playback.

Instructions

Generate SRT/VTT subtitles from audio or video. Cost: 2 credits.

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": {
      "audio_url": "<audio_url>"
    },
    "name": "subtitle"
  }
}

Input Schema

Name	Required	Description	Default
`format`	No	Subtitle format.	srt
`language`	No	Language code.	en
`audio_url`	Yes	URL to audio/video.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv0.3.1Oct 7, 2026

changedInput schema / properties / audio_url / description

Previous value: -"URL to audio or video file"New value: +"URL to audio/video."

changedInput schema / properties / format / description

Previous value: -"srt or vtt"New value: +"Subtitle format."

addedInput schema / properties / format / enum
```
Added value: +[
+  "srt",
+  "vtt"
+]
```

addedInput schema / properties / language

Added value: +{
+  "default": "en",
+  "description": "Language code.",
+  "type": "string"
+}

First observedv0.3.0May 13, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full behavioral burden. It discloses the cost (2 credits) and output formats, but omits authentication needs, async behavior, file-size limits, and what the tool actually returns.

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 short sentences, front-loaded with purpose and followed by a critical cost note. Every sentence earns its place with no wasteful wording.

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

Completeness3/5

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

The description covers the core purpose and pricing, and the input schema is fully documented. However, with no output schema present, it does not explain what the tool returns (subtitle text, file URL, etc.) or whether the operation is synchronous, leaving a meaningful 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 description coverage is 100%, so the schema already explains all three parameters. The description adds only a general mention of audio/video input and SRT/VTT output, without syntax or format details beyond the schema's own enum and defaults.

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?

The description gives a specific verb and resource: generate SRT/VTT subtitles from audio or video. However, it does not distinguish this tool from nearby siblings like transcribe or stt, leaving the agent to infer the boundary.

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

Usage Guidelines2/5

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

There is no when-to-use guidance, no when-not-to-use guidance, and no reference to alternatives such as transcribe or stt. The agent must infer that this is for subtitle generation rather than plain transcription.

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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