KeyError: 'command' in add_mcp_server when running tiny-agent due to incorrect params structure #3203
Description
Describe the bug
When attempting to run tiny-agent, the following error is thrown:
An unexpected error occurred: 'command'
Traceback (most recent call last):
...
File "huggingface_hub/inference/_mcp/mcp_client.py", line 162, in add_mcp_server
logger.info(f"Connecting to stdio MCP server with command: {params['command']} {params.get('args', [])}")
~~~~~~^^^^^^^^^^^
KeyError: 'command'
The issue occurs because the function add_mcp_server expects params to be structured as: {'command': 'npx', 'args': ['@playwright/mcp@latest']}
However, the actual input passed is: {'config': {'command': 'npx', 'args': ['@playwright/mcp@latest']}} This causes the function to attempt accessing params['command'], which results in a KeyError.
Reproduction
Run tiny-agent with a config containing:
{
"model": "Qwen/Qwen2.5-72B-Instruct",
"provider": "nebius",
"servers": [
{
"type": "stdio",
"config": {
"command": "npx",
"args": ["@playwright/mcp@latest"]
}
}
]
}Observe the KeyError: 'command'
Logs
An unexpected error occurred: 'command'
Traceback (most recent call last):
File "/Users/userx/Code/mcp_server_test/.venv/lib/python3.11/site-packages/huggingface_hub/inference/_mcp/cli.py", line 134, in run_agent
await agent.load_tools()
File "/Users/userx/Code/mcp_server_test/.venv/lib/python3.11/site-packages/huggingface_hub/inference/_mcp/agent.py", line 58, in load_tools
await self.add_mcp_server(**cfg)
File "/Users/md/Code/mcp_server_test/.venv/lib/python3.11/site-packages/huggingface_hub/inference/_mcp/mcp_client.py", line 162, in add_mcp_server
logger.info(f"Connecting to stdio MCP server with command: {params['command']} {params.get('args', [])}")
~~~~~~^^^^^^^^^^^
KeyError: 'command'
An unexpected error occurred: 'command'System info
- huggingface_hub version: 0.33.2
- Platform: macOS-15.5-arm64-arm-64bit
- Python version: 3.11.13
- Running in iPython ?: No
- Running in notebook ?: No
- Running in Google Colab ?: No
- Running in Google Colab Enterprise ?: No
- Token path ?: /Users/userx/.cache/huggingface/token
- Has saved token ?: True
- Who am I ?: mihirdeo16
- Configured git credential helpers: osxkeychain, store
- FastAI: N/A
- Tensorflow: N/A
- Torch: N/A
- Jinja2: N/A
- Graphviz: N/A
- keras: N/A
- Pydot: N/A
- Pillow: N/A
- hf_transfer: N/A
- gradio: N/A
- tensorboard: N/A
- numpy: N/A
- pydantic: 2.11.7
- aiohttp: 3.12.13
- hf_xet: 1.1.5
- ENDPOINT: https://huggingface.co
- HF_HUB_CACHE: /Users/userx/.cache/huggingface/hub
- HF_ASSETS_CACHE: /Users/userx/.cache/huggingface/assets
- HF_TOKEN_PATH: /Users/muserxd/.cache/huggingface/token
- HF_STORED_TOKENS_PATH: /Users/userx/.cache/huggingface/stored_tokens
- HF_HUB_OFFLINE: False
- HF_HUB_DISABLE_TELEMETRY: False
- HF_HUB_DISABLE_PROGRESS_BARS: None
- HF_HUB_DISABLE_SYMLINKS_WARNING: False
- HF_HUB_DISABLE_EXPERIMENTAL_WARNING: False
- HF_HUB_DISABLE_IMPLICIT_TOKEN: False
- HF_HUB_ENABLE_HF_TRANSFER: False
- HF_HUB_ETAG_TIMEOUT: 10
- HF_HUB_DOWNLOAD_TIMEOUT: 10