Zovo Subtitle Fix

Check subtitles

check_subtitles

Read-onlyIdempotent

Use this when the user asks whether an SRT or VTT subtitle file has problems, or wants a report before fixing it: overlapping cues, zero or negative durations, cues out of order, SRT numbering gaps, empty cues, cues too fast to read (characters per second above max_cps, default 20) and lines longer than max_line_chars (default 42). Takes one attached .srt or .vtt file or the subtitle text. Does not make a file and does not change the subtitles; fix_subtitles does that. Does not check spelling, translation or sync with the audio.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "check_subtitles"
  }
}

Input Schema

Name	Required	Description
`file`	No	The subtitle file: one .srt or .vtt file in UTF-8 or UTF-16 with a byte order mark, e.g. movie.srt.
`max_cps`	No	Reading speed limit in characters per second, 5 to 60, e.g. 17. Default 20.
`subtitle_text`	No	Instead of a file: the subtitle text itself, e.g. "1\n00:00:01,000 --> 00:00:03,000\nHello". Use either file or subtitle_text.
`max_line_chars`	No	Longest line in characters, 20 to 100, e.g. 42 (default).

Output Schema

Name	Required	Description	Default
`cues`	Yes
`file`	Yes
`notes`	Yes
`format`	Yes
`encoding`	Yes
`last_end`	Yes
`overlaps`	Yes
`problems`	Yes
`fast_cues`	Yes
`numbering`	Yes
`empty_cues`	Yes
`long_lines`	Yes
`first_start`	Yes
`suggestions`	Yes
`out_of_order`	Yes
`bad_durations`	Yes
`three_plus_lines`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 8, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description still adds meaningful context beyond them: accepted inputs (one attached .srt or .vtt, or raw subtitle text), the default thresholds applied during checking, and the explicit guarantee that no file is created and nothing is modified. Return structure is left to the output schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the usage condition in the first clause, then packs the check list and the exclusions into a compact block with no filler. It reads as one dense run-on paragraph; splitting the check list and the exclusions would improve scanability slightly, but nothing is redundant.

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

Completeness5/5

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

With an output schema present, annotations covering safety, and full schema parameter coverage, the description only needs to supply purpose, triggers and scope — all of which it does. Nothing an agent needs to select or invoke this tool is missing.

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 file, subtitle_text, max_cps and max_line_chars are all documented in the schema itself. The description only restates the defaults (max_cps 20, max_line_chars 42) and the either/or input choice, adding little beyond structured data. Baseline 3 is appropriate.

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, then enumerates exactly what it detects: overlapping cues, zero/negative durations, out-of-order cues, SRT numbering gaps, empty cues, CPS over max_cps, and lines over max_line_chars. It also explicitly distinguishes itself from fix_subtitles, so an agent can separate the two without opening either schema.

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

Usage Guidelines5/5

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

Gives an explicit trigger ('when the user asks whether an SRT or VTT subtitle file has problems, or wants a report before fixing it'), names the alternative tool and what it does instead, and lists scope exclusions (spelling, translation, audio sync). Both when-to-use and when-not-to-use are covered.

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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