Bug: ChatCompletionAgent fails with Pydantic validation when MCPStdioPlugin is added for azure mcp server

[Pavkum007]

Describe the bug
pydantic\main.py", line 253, in init
validated_self = self.pydantic_validator.validate_python(data, self_instance=self)
pydantic_core.pydantic_core.ValidationError: 1 validation error for ChatCompletionAgent
name
String should match pattern '^[0-9A-Za-z]+$' [type=string_pattern_mismatch, input_value='auth-method', input_type=str]
For further information visit https://errors.pydantic.dev/2.11/v/string_pattern_mismatch

To Reproduce
Here is the code snippet

 async def main():
    # 1. Create the agent
    async with MCPStdioPlugin(
        name="Azure_MCP_Server",
        description="Azure MCP Plugin",
        command="npx",
        args=["-y", "@azure/mcp@latest", "server", "start"],
    ) as my_plugin:
        agent = ChatCompletionAgent(
            service=AzureChatCompletion(),
            name="MyAgent",
            instructions="Answer questions about my Azure resources",
            plugins=[my_plugin],
        )

        for user_input in USER_INPUTS:
            # 2. Create a thread to hold the conversation
            # If no thread is provided, a new thread will be
            # created and returned with the initial response
            thread: ChatHistoryAgentThread | None = None

            print(f"# User: {user_input}")
            # 3. Invoke the agent for a response
            response = await agent.get_response(messages=user_input, thread=thread)
            print(f"# {response.name}: {response} ")
            thread = response.thread

            # 4. Cleanup: Clear the thread
            await thread.delete() if thread else None


if __name__ == "__main__":
    asyncio.run(main())

Expected behavior
It should successfully configure the MCPStdio (MCP server) for azure mcp

Platform

• Language: Python
• Source: Semantic Kernel version 1.28.1
• AI model: Azure OpenAI:GPT-4o
• IDE: VS Code
• OS: Windows

Additional context
Add any other context about the problem here.

[moonbox3]

Hi @Pavkum007,

Semantic Kernel Agents enforce a strict validation rule on the name field: it must match the regex pattern ^[0-9A-Za-z_]+$ (letters, numbers, and underscores only), as stated in the error.

You used a name like auth-method, which contains a hyphen (-) -- not allowed by the regex.

Can you please check where auth-method is getting configured for an agent or plugin name?

[jfernandrezj]

Hi @Pavkum007,

Semantic Kernel Agents enforce a strict validation rule on the name field: it must match the regex pattern ^[0-9A-Za-z_]+$ (letters, numbers, and underscores only), as stated in the error.

You used a name like auth-method, which contains a hyphen (-) -- not allowed by the regex.

Can you please check where auth-method is getting configured for an agent or plugin name?

It comes up as a KernelParameterMetadata directly from azure-mcp-server during registering.

[jfernandrezj]

this is the stack trace, in this case using the sse transport:

web-1 | INFO:mcp.client.sse:Starting post writer with endpoint URL: http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted" web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted" web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted" web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted" web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted" web-1 | INFO:httpx:HTTP Request: POST http://localhost:5008/message?sessionId=XRWtDNLEZLIcyYzcBLStQQ "HTTP/1.1 202 Accepted"

web-1 | ERROR:services.skernel.mcp_connector:Server azure_mcp_server: Error connecting to HTTP MCP server at http://localhost:5008/sse: 1 validation error for KernelParameterMetadata web-1 | name web-1 | String should match pattern '^[0-9A-Za-z_]+$' [type=string_pattern_mismatch, input_value='auth-method', input_type=str] web-1 | For further information visit https://errors.pydantic.dev/2.9/v/string_pattern_mismatch web-1 | ERROR:services.skernel.mcp_connector:Traceback (most recent call last):

web-1 | File "/app/services/skernel/mcp_connector.py", line 137, in _init_http_plugin** web-1 | kernel.add_plugin(self.plugin, plugin_name=f"mcp_{self.name}") web-1 | File "/usr/local/lib/python3.11/site-packages/semantic_kernel/functions/kernel_function_extension.py", line 107, in add_plugin web-1 | self.plugins[plugin_name] = KernelPlugin.from_object( web-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^ web-1 | File "/usr/local/lib/python3.11/site-packages/semantic_kernel/functions/kernel_plugin.py", line 244, in from_object web-1 | functions = [ web-1 | ^ web-1 | File "/usr/local/lib/python3.11/site-packages/semantic_kernel/functions/kernel_plugin.py", line 245, in <listcomp> web-1 | KernelFunctionFromMethod(method=candidate, plugin_name=plugin_name) web-1 | File "/usr/local/lib/python3.11/site-packages/semantic_kernel/functions/kernel_function_from_method.py", line 57, in __init__ web-1 | parameters = [KernelParameterMetadata(**param) for param in method.__kernel_function_parameters__] # type: ignore web-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ web-1 | File "/usr/local/lib/python3.11/site-packages/semantic_kernel/functions/kernel_function_from_method.py", line 57, in <listcomp> web-1 | parameters = [KernelParameterMetadata(**param) for param in method.__kernel_function_parameters__] # type: ignore web-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ web-1 | File "/usr/local/lib/python3.11/site-packages/pydantic/main.py", line 211, in __init__ web-1 | validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self) web-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ web-1 | pydantic_core._pydantic_core.ValidationError: 1 validation error for KernelParameterMetadata web-1 | name web-1 | String should match pattern '^[0-9A-Za-z_]+$' [type=string_pattern_mismatch, input_value='auth-method', input_type=str] web-1 | For further information visit https://errors.pydantic.dev/2.9/v/string_pattern_mismatch web-1 | web-1 | ERROR:services.skernel.mcp_connector:Server azure_mcp_server: Error closing MCP Plugin connection: Attempted to exit cancel scope in a different task than it was entered in