[model-gateway][doc] Add STDIO Explicitly to Example in README

[xuwenyihust]

Motivation

There's a small discrepancy between the README and the current implementation,
The README.md suggests that for an stdio transport, the protocol field is optional and can be inferred from the presence of a command
with example

servers:
  - name: "filesystem"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
    required: false

...
`protocol`: Protocol type (`"sse"` or `"streamable"`; STDIO is inferred from `command`)
...

But i realized that protocol field could be mandatory during McpTransport deserialization, and omitting protocol: "stdio" will cause an error

Modifications

Update README to explictly set protocol as stdio.

Accuracy Tests

Can successfully connect with protocol: "stdio" added.

servers:
  - name: "filesystem"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "./tmp"]
    protocol: "stdio"
    required: false

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.
• Work with maintainers to merge your PR. See the PR Merge Process

[gemini-code-assist]

Summary of Changes

Hello @xuwenyihust, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an inconsistency in the sgl-router's README.md by updating the example configuration and the description of the protocol field. The change ensures that users correctly configure STDIO transport by explicitly specifying protocol: "stdio", preventing potential deserialization errors and improving documentation accuracy.

Highlights

• Documentation Correction: The README.md has been updated to explicitly include protocol: "stdio" in the example configuration for STDIO transport, addressing a discrepancy where the protocol was previously suggested to be inferable.
• Protocol Field Clarification: The description of the protocol field in the documentation has been revised to explicitly list "stdio" as a valid protocol type, alongside "sse" and "streamable", reflecting its mandatory nature for STDIO transport.

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[gemini-code-assist]

Code Review

This pull request correctly addresses a documentation issue in README.md regarding the MCP configuration for stdio transports. The documentation previously suggested that the protocol field was optional, while the implementation requires it to be explicitly declared. The changes update the example and the field description to reflect the correct usage, which is a valuable clarification. I have one minor suggestion to improve the readability of the updated documentation.

[zhaotyer]

Motivation

There's a small discrepancy between the README and the current implementation, The README.md suggests that for an stdio transport, the protocol field is optional and can be inferred from the presence of a command with example

servers:
  - name: "filesystem"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
    required: false

...
`protocol`: Protocol type (`"sse"` or `"streamable"`; STDIO is inferred from `command`)
...

But i realized that protocol field could be mandatory during McpTransport deserialization, and omitting protocol: "stdio" will cause an error

## Modifications Update README to explictly set `protocol` as `stdio`.

Accuracy Tests

Can successfully connect with protocol: "stdio" added.

servers:
  - name: "filesystem"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "./tmp"]
    protocol: "stdio"
    required: false

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.
• Work with maintainers to merge your PR. See the PR Merge Process

This MCP service can start normally, but how do I use it?
I start filesystem mcp and qwen3-30b-a3b-2507-instruct
Start command：
python3 -m sglang_router.launch_router --host 0.0.0.0 --port 30000 --mcp-config-path ./mcp-config.yaml --policy cache_aware --worker-urls http://172.17.124.39:3218
mcp-config.yaml

servers:
  - name: "filesystem"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
    protocol: "stdio"
    required: false

pool:
  max_connections: 100
  idle_timeout: 300

inventory:
  enable_refresh: true
  tool_ttl: 300
  refresh_interval: 300

and test_mcp.py

import openai

# 配置客户端
client = openai.OpenAI(
    base_url="http://localhost:30000/v1",
    api_key="not-used",
)

# 正确的filesystem MCP工具定义
filesystem_tool = {
    "type": "mcp",
    "server_label": "filesystem",
    "server_description": "Filesystem access server",
    "require_approval": "never",
    "server_url": "stdio://filesystem",  # 必须包含server_url
}

# 发送请求
try:
    response = client.responses.create(
        model="atom",
        input="请列出 /tmp 目录中的所有文件",
        tools=[filesystem_tool],
        stream=False,
        tool_choice="auto",
    )
    
    print(f"请求成功: {response.id}")
    print(f"状态: {response.status}")
    
    # 处理响应...
    
except Exception as e:
    print(f"错误: {e}")

model server error log:

[2026-01-28 09:17:25] INFO:     10.224.1.1:13249 - "POST /v1/responses HTTP/1.1" 500 Internal Server Error
[2026-01-28 09:17:25] ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/dist-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/applications.py", line 1139, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/applications.py", line 107, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/cors.py", line 85, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/exceptions.py", line 63, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 716, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 736, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 290, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 119, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 105, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 385, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 284, in run_endpoint_function
    return await dependant.call(**values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/sgl-workspace/sglang/python/sglang/srt/entrypoints/http_server.py", line 1272, in v1_responses_request
    request_obj = ResponsesRequest(**request)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/pydantic/main.py", line 250, in __init__
    validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 1 validation error for ResponsesRequest
tools.0.type
  Input should be 'web_search_preview' or 'code_interpreter' [type=literal_error, input_value='mcp', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
[2026-01-28 09:17:25] INFO:     10.224.1.1:18446 - "POST /v1/responses HTTP/1.1" 500 Internal Server Error
[2026-01-28 09:17:25] ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/dist-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/applications.py", line 1139, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/applications.py", line 107, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/cors.py", line 85, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/middleware/exceptions.py", line 63, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 716, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 736, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/routing.py", line 290, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 119, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.12/dist-packages/starlette/_exception_handler.py", line 42, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 105, in app
    response = await f(request)
               ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 385, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/fastapi/routing.py", line 284, in run_endpoint_function
    return await dependant.call(**values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/sgl-workspace/sglang/python/sglang/srt/entrypoints/http_server.py", line 1272, in v1_responses_request
    request_obj = ResponsesRequest(**request)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/pydantic/main.py", line 250, in __init__
    validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 1 validation error for ResponsesRequest
tools.0.type
  Input should be 'web_search_preview' or 'code_interpreter' [type=literal_error, input_value='mcp', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error

gateway error log:

026-01-28 09:16:52  INFO http_request{method=GET uri=/workers version=HTTP/1.1 module="smg" request_id="req-8nROlzEtKCBbsAUMJSHp5VNP"}: smg::request: /home/runner/work/sglang/sglang/src/middleware.rs:310: started processing request
2026-01-28 09:16:52  INFO http_request{method=GET uri=/workers version=HTTP/1.1 module="smg" request_id="req-8nROlzEtKCBbsAUMJSHp5VNP" status_code=200 latency=323}: smg::response: /home/runner/work/sglang/sglang/src/middleware.rs:359: finished processing request
2026-01-28 09:17:24  INFO http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-SN7quU9R2BCCTOJbw837wk5l"}: smg::request: /home/runner/work/sglang/sglang/src/middleware.rs:310: started processing request
2026-01-28 09:17:24 ERROR http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-SN7quU9R2BCCTOJbw837wk5l" status_code=500 latency=452391}: smg::response: /home/runner/work/sglang/sglang/src/middleware.rs:349: request failed with server error
2026-01-28 09:17:25  INFO http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-bFz41QezkAXL3EWPrHbRlfGj"}: smg::request: /home/runner/work/sglang/sglang/src/middleware.rs:310: started processing request
2026-01-28 09:17:25  INFO http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-bFz41QezkAXL3EWPrHbRlfGj"}: smg::core::circuit_breaker: /home/runner/work/sglang/sglang/src/core/circuit_breaker.rs:286: Circuit breaker state transition: closed -> open
2026-01-28 09:17:25 ERROR http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-bFz41QezkAXL3EWPrHbRlfGj" status_code=500 latency=418309}: smg::response: /home/runner/work/sglang/sglang/src/middleware.rs:349: request failed with server error
2026-01-28 09:17:26  INFO http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-OAXbgxK6X850puuUQSwKZum5"}: smg::request: /home/runner/work/sglang/sglang/src/middleware.rs:310: started processing request
2026-01-28 09:17:27 ERROR http_request{method=POST uri=/v1/responses version=HTTP/1.1 module="smg" request_id="resp-OAXbgxK6X850puuUQSwKZum5" status_code=503 latency=422915}: smg::response: /home/runner/work/sglang/sglang/src/middleware.rs:349: request failed with server error

I want to know how to test Filesystem MCP?
@xuwenyihust