Caption File Check
REMOTE · POWMCP.COM · SCANNED SEP 25
Parse WebVTT, SRT, or TTML for conformance, timing, overlaps, line length, and reading speed.
Available components
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. How we score → Why this is hard to score →
Endpoint Security74
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability64
- AI-judged instruction clarity (excellent).Pass
- 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. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management50
- Stability observed for 15 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 2 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
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.
remote · powmcp.com
claude mcp add --transport http com-powmcp-caption-file-check 'https://powmcp.com/caption-file-check/mcp'
{
"mcpServers": {
"com-powmcp-caption-file-check": {
"url": "https://powmcp.com/caption-file-check/mcp"
}
}
} {
"servers": {
"com-powmcp-caption-file-check": {
"type": "http",
"url": "https://powmcp.com/caption-file-check/mcp"
}
}
} [mcp_servers.com-powmcp-caption-file-check] url = "https://powmcp.com/caption-file-check/mcp"
{
"$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 mcp add com-powmcp-caption-file-check --url 'https://powmcp.com/caption-file-check/mcp' --transport streamable-http
mcp_servers:
com-powmcp-caption-file-check:
url: "https://powmcp.com/caption-file-check/mcp" {
"McpServers": {
"com-powmcp-caption-file-check": {
"Transport": "http",
"Url": "https://powmcp.com/caption-file-check/mcp"
}
}
} assistant mcp add com-powmcp-caption-file-check -t streamable-http -u 'https://powmcp.com/caption-file-check/mcp'
{
"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.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 25 Sept 26 +1
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 23 Sept 26 +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.
- 21 Sept 26 +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.
- 19 Sept 26 +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.
- 17 Sept 26 +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.
- 15 Sept 26 +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.
- 12 Sept 26 +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.
- 11 Sept 26 0
- Stability: unverified → 0.03 ▲ functional
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 25 Sept 2026 · Probed https://powmcp.com/caption-file-check/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=powmcp.com | CN=WE1,O=Google Trust Services,C=US | 18 Aug 2026 | 16 Nov 2026 | ECDSA 256 | ECDSA-SHA256 | 86489ad185ea61460e8ec5accd535821 |
| SANs: powmcp.com, *.powmcp.com | ||||||
| CN=WE1,O=Google Trust Services,C=US (CA) | CN=GTS Root R4,O=Google Trust Services LLC,C=US | 13 Dec 2023 | 20 Feb 2029 | ECDSA 256 | ECDSA-SHA384 | 7ff31977972c224a76155d13b6d685e3 |
| CN=GTS Root R4,O=Google Trust Services LLC,C=US (CA) | CN=GlobalSign Root CA,OU=Root CA,O=GlobalSign nv-sa,C=BE | 15 Nov 2023 | 28 Jan 2028 | ECDSA 384 | SHA256-RSA | 7fe530bf331343bedd821610493d8a1b |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of powmcp.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| powmcp.com. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://powmcp.com/caption-file-check/mcp | Verified | 200 | |
| http (plaintext) | http://powmcp.com/caption-file-check/mcp | HTTPS enforced | 308 | https://powmcp.com/caption-file-check/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
caption_check ~520
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.
| Name | Type | Req | Description |
|---|---|---|---|
| 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… |
| Name | Type | Req | Description |
|---|---|---|---|
| bom | string | yes | Byte-order-mark detected: utf-8, utf-16le, utf-16be, or none |
| checkedAt | string | yes | ISO timestamp when the caption result was produced |
| cps | object | yes | Per-cue and summary reading-speed measurements |
| cueCount | number | yes | Number of caption cues retained for checking; payload-less WebVTT cues are omitted by the parser |
| detectedFormat | string | yes | webvtt, srt, or ttml (covers IMSC), detected by content |
| encoding | string | yes | Detected byte encoding of the caption file |
| lineLength | object | yes | Per-line character counts checked against the profile limit |
| pass | boolean | yes | 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 | yes | Reading-speed and line-length profile applied to the caption checks |
| rawCueCount | number | yes | Cues parsed before the 20,000-cue cap; excludes payload-less WebVTT cues dropped by the parser |
| specUsed | string | yes | The dated spec identifier the detected format was checked against |
| structuralErrorCounts | object | yes | Counts of structural findings grouped by severity |
| structuralErrors | array | yes | Spec-parser and IMSC/TTML profile-conformance findings |
| timing | object | yes | Measured retained-cue timing and empty-text findings; WebVTT indices refer to retained cues, not original source positions |
| truncation | array | yes | Markers identifying checks truncated by configured limits |
| ttmlProfile | string | – | IMSC/TTML profile designator declared in the file, when present |
| url | string | yes | The checked caption source: the submitted URL query- and fragment-stripped, or the attached file's name |
No examples provided.
caption_compare ~387
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.
| Name | Type | Req | Description |
|---|---|---|---|
| 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… |
| Name | Type | Req | Description |
|---|---|---|---|
| checkedAt | string | yes | ISO timestamp when the caption result was produced |
| comparison | object | – | Measured differences between the two successfully preflighted tracks |
| notes | array | yes | Notes about incomplete checks or completion under identical limits |
| profile | object | yes | Reading-speed and line-length profile applied to the caption checks |
| tracks | array | yes | The two tracks in input order |
| winner | object | – | Track with fewer weighted structural, timing, reading-speed, and line-length problems |
No examples provided.
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.