MCP Async Skill

MCP Async Skill Generator

Generate reusable Skills from HTTP MCP servers that use async job patterns.

When to Use

• Converting .mcp.json into a packaged Skill (tool info is fetched from catalog)
• Calling async MCP tools: submit → poll status → get result → download
• Integrating image/video generation MCPs (fal.ai, Replicate, etc.)

File Upload (for image/audio/video inputs)

Many MCPs require URL inputs for media files. Use fal_client to upload local files:

# Upload file and get URL (one-liner)
python -c "import fal_client; url=fal_client.upload_file(r'/path/to/file.png'); print(f'URL: {url}')"

# Examples for different platforms:
# Windows
python -c "import fal_client; url=fal_client.upload_file(r'C:\Users\name\image.png'); print(f'URL: {url}')"

# Linux/Mac
python -c "import fal_client; url=fal_client.upload_file('/home/user/image.png'); print(f'URL: {url}')"

# Android (Termux)
python -c "import fal_client; url=fal_client.upload_file('/storage/emulated/0/Download/image.png'); print(f'URL: {url}')"

The returned URL (e.g., https://v3b.fal.media/files/...) can be used in image_url, image_urls, audio_url, etc. parameters.

Supported formats: png, jpg, jpeg, gif, webp, mp3, wav, mp4, webm, etc.

Quick Start

Generate Skill from MCP Config (Recommended)

Tool information is automatically fetched from mcp_tool_catalog.yaml:

python scripts/generate_skill.py \
  --mcp-config /path/to/.mcp.json

Output: .claude/skills/<skill-name>/SKILL.md

The server name in .mcp.json is used to look up tools from the catalog.

Generate Skill with Legacy tools.info

If you have a local tools.info file:

python scripts/generate_skill.py \
  --mcp-config /path/to/.mcp.json \
  --tools-info /path/to/tools.info \
  --name my-mcp-skill

Specify Custom Output Directory

python scripts/generate_skill.py \
  --mcp-config /path/to/.mcp.json \
  --output /custom/path

Direct Async Tool Call

python scripts/mcp_async_call.py \
  --endpoint "https://mcp.example.com/sse" \
  --submit-tool "generate_image" \
  --status-tool "check_status" \
  --result-tool "get_result" \
  --args '{"prompt": "a cat"}' \
  --output ./output

Async Pattern Flow

1. SUBMIT    → POST JSON-RPC → Get session_id
2. STATUS    → Poll with session_id → Wait for "completed"
3. RESULT    → Get download URL
4. DOWNLOAD  → Save file locally

JSON-RPC 2.0 Format

All MCP calls use this structure:

{
  "jsonrpc": "2.0",
  "id": "unique-id",
  "method": "tools/call",
  "params": {
    "name": "tool_name",
    "arguments": { "key": "value" }
  }
}

Input File Formats

.mcp.json

The server name must match a server id in the catalog:

{
  "mcpServers": {
    "t2i-kamui-fal-flux-lora": {
      "type": "http",
      "url": "https://kamui-code.ai/t2i/fal/flux-lora",
      "headers": {
        "KAMUI-CODE-PASS": "your-pass"
      }
    }
  }
}

Or direct format:

{
  "name": "t2i-kamui-fal-flux-lora",
  "url": "https://kamui-code.ai/t2i/fal/flux-lora",
  "auth_header": "KAMUI-CODE-PASS",
  "auth_value": "your-pass"
}

mcp_tool_catalog.yaml (Auto-fetched)

Tool information is fetched from: https://raw.githubusercontent.com/Yumeno/kamuicode-config-manager/main/mcp_tool_catalog.yaml

The catalog contains 266+ servers with tool definitions:

servers:
  - id: t2i-kamui-fal-flux-lora
    status: online
    tools:
      - name: flux_lora_submit
        description: Submit Flux LoRA image generation request
        inputSchema:
          properties:
            prompt:
              description: Image prompt
              type: string
          required:
            - prompt
          type: object

tools.info (Legacy)

Optional, for backward compatibility:

[
  {
    "name": "generate",
    "description": "Generate content",
    "inputSchema": {
      "type": "object",
      "properties": {
        "prompt": { "type": "string", "description": "Input prompt" }
      },
      "required": ["prompt"]
    }
  }
]

Script Reference

scripts/mcp_async_call.py

Main async MCP caller with full flow automation.

Options:

• --endpoint, -e: MCP server URL
• --submit-tool: Tool name for job submission
• --status-tool: Tool name for status checking
• --result-tool: Tool name for result retrieval
• --args, -a: Submit arguments as JSON string
• --args-file: Load arguments from JSON file
• --output, -o: Output directory (default: ./output)
• --poll-interval: Seconds between polls (default: 2.0)
• --max-polls: Maximum poll attempts (default: 300)
• --header: Add custom header (format: Key:Value)
• --config, -c: Load endpoint from .mcp.json

scripts/generate_skill.py

Generate complete Skill from MCP specifications.

Options:

• --mcp-config, -m: Path to .mcp.json (required)
• --tools-info, -t: Path to tools.info (optional, legacy mode)
• --output, -o: Output directory
• --name, -n: Skill name (auto-detected if omitted)
• --catalog-url: Custom catalog URL (default: GitHub raw URL)

Requirements:

• pip install pyyaml requests (for catalog fetching)

Generated Skill Structure

Skills are generated to .claude/skills/<skill-name>/:

.claude/skills/
└── skill-name/
    ├── SKILL.md              # Usage documentation
    ├── scripts/
    │   ├── mcp_async_call.py # Core async caller
    │   └── skill_name.py     # Convenience wrapper
    └── references/
        ├── mcp.json          # Original MCP config
        └── tools.json        # Original tool specs

Common Status Values

Programmatic Usage

from scripts.mcp_async_call import run_async_mcp_job

result = run_async_mcp_job(
    endpoint="https://mcp.example.com/sse",
    submit_tool="generate",
    submit_args={"prompt": "sunset over mountains"},
    status_tool="status",
    result_tool="result",
    output_path="./output",
    poll_interval=2.0,
    max_polls=300,
)

print(result["saved_path"])  # Path to downloaded file

Error Handling

The script handles:

• JSON-RPC errors in response
• Job failures (status: failed/error)
• Timeout after max polls
• Download failures

All errors raise exceptions with descriptive messages.