# Caption File Check (remote · powmcp.com)

Parse WebVTT, SRT, or TTML for conformance, timing, overlaps, line length, and reading speed.

- Trust score: 76/100 (medium)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-25

## Components

- remote · `powmcp.com`: 76/100 (this document), [markdown](https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp.md), [page](https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp)

## Channel facts

- Endpoint: `https://powmcp.com/caption-file-check/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `0.3.3`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-25.

- **Endpoint Security**: 74/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS is enforced; there's no plaintext access path.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 64/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 1245 tokens (~622/item across 2 items; 2 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 50/100
  - Stability observed for 15 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 2 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the Caption File Check MCP server?

Caption File Check is a hosted endpoint at https://powmcp.com/caption-file-check/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http com-powmcp-caption-file-check 'https://powmcp.com/caption-file-check/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "com-powmcp-caption-file-check": {
      "url": "https://powmcp.com/caption-file-check/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "com-powmcp-caption-file-check": {
      "type": "http",
      "url": "https://powmcp.com/caption-file-check/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.com-powmcp-caption-file-check]
url = "https://powmcp.com/caption-file-check/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "com-powmcp-caption-file-check": {
      "type": "remote",
      "url": "https://powmcp.com/caption-file-check/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add com-powmcp-caption-file-check --url 'https://powmcp.com/caption-file-check/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  com-powmcp-caption-file-check:
    url: "https://powmcp.com/caption-file-check/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "com-powmcp-caption-file-check": {
      "Transport": "http",
      "Url": "https://powmcp.com/caption-file-check/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add com-powmcp-caption-file-check -t streamable-http -u 'https://powmcp.com/caption-file-check/mcp'
```

### Other

```json
{
  "mcpServers": {
    "com-powmcp-caption-file-check": {
      "type": "http",
      "url": "https://powmcp.com/caption-file-check/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-25 (score 76, +1)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-09-23 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-21 (score 74, +1)

No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-19 (score 73, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-17 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-15 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-12 (score 70, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-11 (score 69, 0)

- [functional improvement] Stability: unverified → 0.03

## MCP tools (2)

### `caption_check` (~520 tokens)

Preflight one caption or subtitle file before delivery. Attach a WebVTT (.vtt), SRT (.srt), or TTML/IMSC (.ttml/.xml) caption file in chat or give a publicly fetchable URL and it downloads the artifact under an SSRF-guarded, 2 MB-capped fetch, detects the format by content and the byte encoding and BOM, then parses it with the real spec engine (the WebVTT spec parser, a dedicated SRT parser, or the imscJS TTML/IMSC profile engine) and returns deterministic evidence: pass/fail, cue count, structural spec and IMSC profile-conformance errors, overlapping / negative / out-of-order / empty cues, per-line length, and per-cue and summary reading speed (CPS) against a named platform profile (netflix-adult-20, netflix-children-17, youtube, ebu-tt). It reports only source-file conformance, timing, encoding, and reading-speed facts against a dated profile. It does not judge translation quality, transcription accuracy, or synchronization against the video. An arbitrary XML or text file that is not a caption track returns an explicit unsupported-format error. Fetching and parsing a full-length track can take up to 60 seconds. WebVTT limitation: the parser drops payload-less cues; cue counts, indices, timing checks and comparisons cover retained cues only, not those omitted cues.

Input parameters:

- `file` (object): A caption file attached in chat (WebVTT, SRT, or TTML/IMSC), detected by content not extension. Provide either this or url, never both.
- `profile`: Named reading-speed profile to judge CPS and line length against. netflix-adult-20 (default, 20 CPS) and netflix-children-17 (17 CPS) are spec-backed; youtube and ebu-tt are advisory ~17 CPS heuristi…
- `url` (string): A publicly fetchable HTTP(S) URL of a WebVTT, SRT, or TTML/IMSC caption file, detected by content not extension. Provide either this or an attached file, never both. Query strings are allowed but nev…

Output parameters:

- `bom` (string): Byte-order-mark detected: utf-8, utf-16le, utf-16be, or none
- `checkedAt` (string): ISO timestamp when the caption result was produced
- `cps` (object): Per-cue and summary reading-speed measurements
- `cueCount` (number): Number of caption cues retained for checking; payload-less WebVTT cues are omitted by the parser
- `detectedFormat` (string): webvtt, srt, or ttml (covers IMSC), detected by content
- `encoding` (string): Detected byte encoding of the caption file
- `lineLength` (object): Per-line character counts checked against the profile limit
- `pass` (boolean): True when the file passes all checked format, timing, line-length and reading-speed criteria for the selected profile. False can include an advisory readability threshold breach, not just a specifica…
- `profile` (object): Reading-speed and line-length profile applied to the caption checks
- `rawCueCount` (number): Cues parsed before the 20,000-cue cap; excludes payload-less WebVTT cues dropped by the parser
- `specUsed` (string): The dated spec identifier the detected format was checked against
- `structuralErrorCounts` (object): Counts of structural findings grouped by severity
- `structuralErrors` (array): Spec-parser and IMSC/TTML profile-conformance findings
- `timing` (object): Measured retained-cue timing and empty-text findings; WebVTT indices refer to retained cues, not original source positions
- `truncation` (array): Markers identifying checks truncated by configured limits
- `ttmlProfile` (string): IMSC/TTML profile designator declared in the file, when present
- `url` (string): The checked caption source: the submitted URL query- and fragment-stripped, or the attached file's name

### `caption_compare` (~387 tokens)

Compare exactly two caption or subtitle files under identical bounded checks: an original versus its translated track, before versus after a timing fix, or a format migration. Attach two WebVTT, SRT, or TTML/IMSC caption files in chat or give two publicly fetchable URLs and it runs the same SSRF-guarded, 2 MB-capped preflight as caption_check on each, then aligns them by cue index and reports side-by-side pass status, detected-format and encoding differences, the cue-count delta, timing drift and overlap differences, reading-speed (CPS) regressions, structural-error deltas, and a winner only when the measured checks separate the two. Use caption_check for a single file. It reports only source-file conformance, timing, encoding, and reading-speed facts against a dated profile: never translation quality, transcription accuracy, or sync against the video. Fetching and parsing two live files can take up to 60 seconds. WebVTT limitation: the parser drops payload-less cues; cue counts, indices, timing checks and comparisons cover retained cues only, not those omitted cues.

Input parameters:

- `files` (array): Exactly two caption files attached in chat to compare, in the order they should appear side by side (for example original then translated). Provide either this or urls, never both.
- `profile`: Named reading-speed profile applied to both tracks. netflix-adult-20 (default), netflix-children-17, youtube, ebu-tt.
- `urls` (array): Exactly two public caption URLs to compare, in the order they should appear side by side (for example original then translated). Provide either this or files, never both. STRICT RULE: Caption compar…

Output parameters:

- `checkedAt` (string): ISO timestamp when the caption result was produced
- `comparison` (object): Measured differences between the two successfully preflighted tracks
- `notes` (array): Notes about incomplete checks or completion under identical limits
- `profile` (object): Reading-speed and line-length profile applied to the caption checks
- `tracks` (array): The two tracks in input order
- `winner` (object): Track with fewer weighted structural, timing, reading-speed, and line-length problems

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp#diagnostics

## Score history

- 2026-09-25: 76
- 2026-09-24: 75
- 2026-09-23: 75
- 2026-09-22: 74
- 2026-09-21: 74
- 2026-09-20: 73
- 2026-09-19: 73
- 2026-09-18: 72
- 2026-09-17: 72
- 2026-09-16: 71
- 2026-09-15: 71
- 2026-09-14: 70
- 2026-09-13: 70
- 2026-09-12: 70
- 2026-09-11: 69
- 2026-09-10: 69

## Common questions

### What is the Caption File Check MCP server?

Caption File Check is an MCP server listed in the public MCP registry as com.powmcp/caption-file-check. Parse WebVTT, SRT, or TTML for conformance, timing, overlaps, line length, and reading speed. This page covers its hosted endpoint (https://powmcp.com/caption-file-check/mcp).

### Is the Caption File Check MCP server safe to use?

Caption File Check scores 76 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the Caption File Check MCP server expose?

Caption File Check exposes 2 tools: caption_check, caption_compare. Their descriptions and schemas cost roughly 907 tokens of context every time the server is loaded.

### Does the Caption File Check MCP server require authentication?

No. We connected to Caption File Check without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the Caption File Check MCP server still maintained?

Caption File Check is still listed as active in the MCP registry. We last reached this channel on 25 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://powmcp.com/caption-file-check/mcp
- Repository: https://github.com/powmcp/mcp-server-guide
- Website: https://powmcp.com/apps/caption-file-check/
- Changelog RSS feed: https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp.json
- HTML version of this page: https://verifymcp.io/servers/com-powmcp-caption-file-check/caption-file-check-mcp