Best Caption Generator

Skip the learning curve of professional editing software. Describe what you want — add captions in English and Spanish with auto-sync — and get captioned vid...

Security Scan

The skill's stated purpose (cloud captioning) matches its network calls and single required credential, but there are inconsistencies and privacy-relevant behaviors (auto-generating and storing tokens, metadata claiming a user config path, instructions to hide token values) that warrant caution before installing.

Purpose & Capability

The skill is an instruction-only captioning client that talks to nemo-video's API and requires a NEMO_TOKEN — that aligns with the stated purpose. However, the SKILL.md frontmatter lists a config path (~/.config/nemovideo/) while the registry metadata reported no required config paths, indicating a metadata mismatch that should be clarified.

Instruction Scope

Runtime instructions tell the agent to automatically obtain an anonymous token, create and store a session, and keep token values out of the user's view. Automatically acquiring and persisting credentials and explicitly hiding token values from users increases opacity and could be abused for credential persistence or exfiltration if the backend or skill were malicious.

Install Mechanism

No install spec and no code files — this is an instruction-only skill, so nothing will be written to disk by an installer. That lowers the filesystem footprint and attack surface.

Credentials

Only one credential (NEMO_TOKEN) is declared, which is appropriate for a cloud captioning service. But the skill both checks for NEMO_TOKEN and includes instructions to obtain and set one, so you should confirm how/where the token and session_id will be stored and whether an externally-provided NEMO_TOKEN could be overwritten.

Persistence & Privilege

always is false (normal), but the frontmatter references a user config path (~/.config/nemovideo/) and the runtime asks to store session tokens for later requests. The combination of persistently stored tokens and a declared config path (which conflicts with registry metadata) raises a concern about what will be written or read from the user's home configuration.

What to consider before installing

This skill largely does what it says (uploads videos to an external API and returns captioned outputs), but there are a few things to check before installing or using it: - Ask the publisher for provenance: there is no homepage/source listed. Confirm the service domain (mega-api-prod.nemovideo.ai) is legitimate for the vendor. - Clarify the config-path mismatch: the SKILL.md frontmatter mentions ~/.config/nemovideo/ but the registry metadata did not. Ask whether the skill will read or write that directory and what it stores there. - Confirm token handling: the skill will auto-request an anonymous NEMO_TOKEN and instruct you not to display token values. Request transparency about where tokens/session IDs are stored (in memory, environment, or on disk) and whether they persist beyond the 7-day anonymous token life. Do not provide any sensitive or long-lived credentials as NEMO_TOKEN unless you trust the publisher. - Consider privacy of uploads: videos are uploaded to an external cloud GPU service. If your videos contain sensitive data, avoid using this skill or test with non-sensitive content first. - Mitigations: run the skill in an isolated environment, use a throwaway account or ephemeral token, and ask the developer to remove the instruction that hides token values (or to log only non-sensitive metadata). If you cannot verify the publisher or storage behavior, treat the skill as untrusted.

Getting Started

Share your video files and I'll get started on AI caption generation. Or just tell me what you're thinking.

Try saying:

• "add my video files"
• "export 1080p MP4"
• "add captions in English and Spanish"

First-Time Connection

When a user first opens this skill, connect to the processing backend automatically. Briefly let them know (e.g. "Setting up...").

Authentication: Check if NEMO_TOKEN is set in the environment. If it is, skip to step 2.

1. Obtain a free token: Generate a random UUID as client identifier. POST to https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with header X-Client-Id set to that UUID. The response data.token is your NEMO_TOKEN — 100 free credits, valid 7 days.
2. Create a session: POST to https://mega-api-prod.nemovideo.ai/api/tasks/me/with-session/nemo_agent with Authorization: Bearer <token>, Content-Type: application/json, and body {"task_name":"project","language":"<detected>"}. Store the returned session_id for all subsequent requests.

Keep setup communication brief. Don't display raw API responses or token values to the user.

Best Caption Generator — Auto-Generate Captions for Videos

Drop your video files in the chat and tell me what you need. I'll handle the AI caption generation on cloud GPUs — you don't need anything installed locally.

Here's a typical use: you send a a 3-minute YouTube tutorial video, ask for add captions in English and Spanish with auto-sync, and about 30-60 seconds later you've got a MP4 file ready to download. The whole thing runs at 1080p by default.

One thing worth knowing — shorter clips under 5 minutes generate captions significantly faster.

Matching Input to Actions

User prompts referencing best caption generator, aspect ratio, text overlays, or audio tracks get routed to the corresponding action via keyword and intent classification.

User says...	Action	Skip SSE?
"export" / "导出" / "download" / "send me the video"	→ §3.5 Export	✅
"credits" / "积分" / "balance" / "余额"	→ §3.3 Credits	✅
"status" / "状态" / "show tracks"	→ §3.4 State	✅
"upload" / "上传" / user sends file	→ §3.2 Upload	✅
Everything else (generate, edit, add BGM…)	→ §3.1 SSE	❌

Cloud Render Pipeline Details

Each export job queues on a cloud GPU node that composites video layers, applies platform-spec compression (H.264, up to 1080x1920), and returns a download URL within 30-90 seconds. The session token carries render job IDs, so closing the tab before completion orphans the job.

Three attribution headers are required on every request and must match this file's frontmatter:

Header	Value
X-Skill-Source	best-caption-generator
X-Skill-Version	frontmatter version
X-Skill-Platform	auto-detect: clawhub / cursor / unknown from install path

Include Authorization: Bearer <NEMO_TOKEN> and all attribution headers on every request — omitting them triggers a 402 on export.

API base: https://mega-api-prod.nemovideo.ai

Create session: POST /api/tasks/me/with-session/nemo_agent — body {"task_name":"project","language":"<lang>"} — returns task_id, session_id.

Send message (SSE): POST /run_sse — body {"app_name":"nemo_agent","user_id":"me","session_id":"<sid>","new_message":{"parts":[{"text":"<msg>"}]}} with Accept: text/event-stream. Max timeout: 15 minutes.

Upload: POST /api/upload-video/nemo_agent/me/<sid> — file: multipart -F "files=@/path", or URL: {"urls":["<url>"],"source_type":"url"}

Credits: GET /api/credits/balance/simple — returns available, frozen, total

Session state: GET /api/state/nemo_agent/me/<sid>/latest — key fields: data.state.draft, data.state.video_infos, data.state.generated_media

Export (free, no credits): POST /api/render/proxy/lambda — body {"id":"render_<ts>","sessionId":"<sid>","draft":<json>,"output":{"format":"mp4","quality":"high"}}. Poll GET /api/render/proxy/lambda/<id> every 30s until status = completed. Download URL at output.url.

Supported formats: mp4, mov, avi, webm, mkv, jpg, png, gif, webp, mp3, wav, m4a, aac.

Reading the SSE Stream

Text events go straight to the user (after GUI translation). Tool calls stay internal. Heartbeats and empty data: lines mean the backend is still working — show "⏳ Still working..." every 2 minutes.

About 30% of edit operations close the stream without any text. When that happens, poll /api/state to confirm the timeline changed, then tell the user what was updated.

Backend Response Translation

The backend assumes a GUI exists. Translate these into API actions:

Backend says	You do
"click [button]" / "点击"	Execute via API
"open [panel]" / "打开"	Query session state
"drag/drop" / "拖拽"	Send edit via SSE
"preview in timeline"	Show track summary
"Export button" / "导出"	Execute export workflow

Draft field mapping: t=tracks, tt=track type (0=video, 1=audio, 7=text), sg=segments, d=duration(ms), m=metadata.

Timeline (3 tracks): 1. Video: city timelapse (0-10s) 2. BGM: Lo-fi (0-10s, 35%) 3. Title: "Urban Dreams" (0-3s)

Error Codes

• 0 — success, continue normally
• 1001 — token expired or invalid; re-acquire via /api/auth/anonymous-token
• 1002 — session not found; create a new one
• 2001 — out of credits; anonymous users get a registration link with ?bind=<id>, registered users top up
• 4001 — unsupported file type; show accepted formats
• 4002 — file too large; suggest compressing or trimming
• 400 — missing X-Client-Id; generate one and retry
• 402 — free plan export blocked; not a credit issue, subscription tier
• 429 — rate limited; wait 30s and retry once

Tips and Tricks

The backend processes faster when you're specific. Instead of "make it look better", try "add captions in English and Spanish with auto-sync" — concrete instructions get better results.

Max file size is 500MB. Stick to MP4, MOV, AVI, WebM for the smoothest experience.

Export as MP4 for widest compatibility across platforms and devices.

Common Workflows

Quick edit: Upload → "add captions in English and Spanish with auto-sync" → Download MP4. Takes 30-60 seconds for a 30-second clip.

Batch style: Upload multiple files in one session. Process them one by one with different instructions. Each gets its own render.

Iterative: Start with a rough cut, preview the result, then refine. The session keeps your timeline state so you can keep tweaking.