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---
name: python-mcp-server-generator
description: 'Generate a complete MCP server project in Python with tools, resources, and proper configuration'
description: 'Use this skill when the user wants to create a new Model Context Protocol (MCP) server in Python. Also use it to expose Python functions, an API, or a database to AI clients as MCP tools. The skill makes a uv project with the MCP Python SDK v2 (MCPServer), typed tools, in-memory tests, and client configuration. Do not use it for an MCP client or for a server in another language.'
compatibility: 'Requires uv, Python 3.10 or later, and network access to install packages. The MCP Inspector also requires Node.js.'
---
# Generate Python MCP Server
# Python MCP Server Generator
Create a complete Model Context Protocol (MCP) server in Python with the following specifications:
Create a Model Context Protocol (MCP) server in Python with the official [MCP Python SDK](https://github.com/modelcontextprotocol/python-sdk) v2. SDK v2 supports the MCP specification revision [2026-07-28](https://modelcontextprotocol.io/specification/2026-07-28). The same server also serves clients that use earlier revisions.
## Requirements
## Workflow
1. **Project Structure**: Create a new Python project with proper structure using uv
2. **Dependencies**: Include mcp[cli] package with uv
3. **Transport Type**: Choose between stdio (for local) or streamable-http (for remote)
4. **Tools**: Create at least one useful tool with proper type hints
5. **Error Handling**: Include comprehensive error handling and validation
Copy this checklist and track your progress:
## Implementation Details
- [ ] Step 1: Create the project.
- [ ] Step 2: Write the server.
- [ ] Step 3: Write the tests.
- [ ] Step 4: Run the tests until they pass.
- [ ] Step 5: Configure the client.
### Project Setup
- Initialize with `uv init project-name`
- Add MCP SDK: `uv add "mcp[cli]"`
- Create main server file (e.g., `server.py`)
- Add `.gitignore` for Python projects
- Configure for direct execution with `if __name__ == "__main__"`
### Step 1: Create the project
### Server Configuration
- Use `FastMCP` class from `mcp.server.fastmcp`
- Set server name and optional instructions
- Choose transport: stdio (default) or streamable-http
- For HTTP: optionally configure host, port, and stateless mode
Run these commands:
### Tool Implementation
- Use `@mcp.tool()` decorator on functions
- Always include type hints - they generate schemas automatically
- Write clear docstrings - they become tool descriptions
- Use Pydantic models or TypedDicts for structured outputs
- Support async operations for I/O-bound tasks
- Include proper error handling
```bash
uv init --app --no-package project-name
cd project-name
uv add "mcp[cli]>=2,<3"
uv add --dev pytest
```
### Resource/Prompt Setup (Optional)
- Add resources with `@mcp.resource()` decorator
- Use URI templates for dynamic resources: `"resource://{param}"`
- Add prompts with `@mcp.prompt()` decorator
- Return strings or Message lists from prompts
Then delete `main.py`. The server goes in `server.py`.
### Code Quality
- Use type hints for all function parameters and returns
- Write docstrings for tools, resources, and prompts
- Follow PEP 8 style guidelines
- Use async/await for asynchronous operations
- Implement context managers for resource cleanup
- Add inline comments for complex logic
- Without `--no-package`, uv makes a `src/` package layout, and the tests cannot import `server.py`.
- `uv init` makes the `.gitignore` file. Do not write a different one.
## Example Tool Types to Consider
- Data processing and transformation
- File system operations (read, analyze, search)
- External API integrations
- Database queries
- Text analysis or generation (with sampling)
- System information retrieval
- Math or scientific calculations
### Step 2: Write the server
## Configuration Options
- **For stdio Servers**:
- Simple direct execution
- Test with `uv run mcp dev server.py`
- Install to Claude: `uv run mcp install server.py`
- **For HTTP Servers**:
- Port configuration via environment variables
- Stateless mode for scalability: `stateless_http=True`
- JSON response mode: `json_response=True`
- CORS configuration for browser clients
- Mounting to existing ASGI servers (Starlette/FastAPI)
Start from this template:
## Testing Guidance
- Explain how to run the server:
- stdio: `python server.py` or `uv run server.py`
- HTTP: `python server.py` then connect to `http://localhost:PORT/mcp`
- Test with MCP Inspector: `uv run mcp dev server.py`
- Install to Claude Desktop: `uv run mcp install server.py`
- Include example tool invocations
- Add troubleshooting tips
```python
from mcp.server import MCPServer
from mcp.server.mcpserver.exceptions import ToolError
## Additional Features to Consider
- Context usage for logging, progress, and notifications
- LLM sampling for AI-powered tools
- User input elicitation for interactive workflows
- Lifespan management for shared resources (databases, connections)
- Structured output with Pydantic models
- Icons for UI display
- Image handling with Image class
- Completion support for better UX
mcp = MCPServer("Demo", version="0.1.0")
## Best Practices
- Use type hints everywhere - they're not optional
- Return structured data when possible
- Log to stderr (or use Context logging) to avoid stdout pollution
- Clean up resources properly
- Validate inputs early
- Provide clear error messages
- Test tools independently before LLM integration
Generate a complete, production-ready MCP server with type safety, proper error handling, and comprehensive documentation.
@mcp.tool()
def divide(a: float, b: float) -> float:
"""Divide a by b."""
if b == 0:
raise ToolError("b must not be zero.")
return a / b
if __name__ == "__main__":
mcp.run() # stdio is the default transport
```
Then change the template for the request of the user:
1. Replace `divide` with the tools that the user needs.
2. Give each tool full type hints and a docstring. The SDK makes the input schema from the type hints. The docstring becomes the tool description.
3. Return a Pydantic model or a `TypedDict` when the client needs machine-readable data. The SDK makes the output schema from the return type.
4. Use `async def` for I/O. The SDK runs a sync tool on a worker thread.
5. Mark a read-only tool with `@mcp.tool(annotations=ToolAnnotations(read_only_hint=True))` (from `mcp.types`). Use `destructive_hint=True` for a destructive tool.
6. Add resources (`@mcp.resource("users://{user_id}")`) and prompts (`@mcp.prompt()`) only when the user asks for them.
Use stdio by default. Read [references/streamable-http.md](references/streamable-http.md) only when the user asks for a remote server or an HTTP server.
### Step 3: Write the tests
Put `test_server.py` next to `server.py`. Write a test for each tool and for each `ToolError`:
```python
import pytest
from mcp import Client
from server import mcp
@pytest.mark.anyio
async def test_divide():
async with Client(mcp) as client:
result = await client.call_tool("divide", {"a": 6, "b": 3})
assert result.structured_content == {"result": 2.0}
@pytest.mark.anyio
async def test_divide_by_zero():
async with Client(mcp) as client:
result = await client.call_tool("divide", {"a": 1, "b": 0})
assert result.is_error
assert "must not be zero" in result.content[0].text
```
- The in-memory `Client` needs no subprocess and no port. It connects with the 2026-07-28 revision.
- The `mcp` package installs `anyio`, which supplies the `anyio` marker. Do not add `pytest-asyncio`.
### Step 4: Run the tests until they pass
1. Run `uv run pytest`.
2. If a test fails, read the error. Fix the server or the test.
3. Run `uv run pytest` again.
4. Continue only when all tests pass.
### Step 5: Configure the client
For VS Code, write `.vscode/mcp.json`:
```json
{
"servers": {
"demo": {
"type": "stdio",
"command": "uv",
"args": ["--directory", "/absolute/path/to/project", "run", "server.py"]
}
}
}
```
For Claude Desktop, run `uv run mcp install server.py`.
Tell the user these commands:
- `uv run server.py` starts the stdio server. The server waits for a host on stdin and prints nothing.
- `uv run mcp dev server.py` opens the MCP Inspector. The Inspector needs Node.js.
## Gotchas
SDK v2 and the 2026-07-28 revision changed many SDK v1 patterns. Do not copy SDK v1 examples.
- SDK v2 removed `FastMCP` and `mcp.server.fastmcp`. Import the server class with `from mcp.server import MCPServer`.
- Import `Context`, `Image`, `Audio`, `Resolve`, `Elicit`, `ElicitationResult`, `AcceptedElicitation`, `Message`, `UserMessage`, and `AssistantMessage` from `mcp.server.mcpserver`.
- Give the server name as the first `MCPServer` argument. Give all other constructor arguments as keyword arguments. Their positional order changed in SDK v2.
- Set `version`. If you do not set it, the server reports an empty version.
- Give the transport options (`transport`, `host`, `port`, `json_response`, `stateless_http`, `transport_security`) to `run()`, not to `MCPServer(...)`.
- The SDK v2 types use snake_case fields, for example `read_only_hint`, `structured_content`, and `is_error`.
- Raise `ToolError` for an error that the model must read. For other exceptions, the model gets only a generic error message.
- Do not raise `MCPError` for a tool failure. The client gets a protocol error, not a tool result with `is_error`. Many hosts do not show this error to the model.
- In a stdio server, stdout is the protocol channel. Do not call `print()`. Log to stderr with the `logging` module.
- Do not use `ctx.elicit()`. It fails on a 2026-07-28 connection. For user input during a tool call, annotate a parameter with `Resolve(fn)`. Return `Elicit(message, Model)` from `fn`.
- Send list change notifications with `await ctx.notify_tools_changed()`. A 2026-07-28 connection drops `ctx.session.send_tool_list_changed()`.
- For stdio and HTTP, the lifespan runs one time, when the server starts. Each in-memory `Client(mcp)` in a test runs the lifespan again. Read its object with `ctx.request_context.lifespan_context`.
- The 2026-07-28 revision deprecates these features ([SEP-2577](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577)). Do not add them to a new server:
- **Sampling** (`ctx.session.create_message()`): Call the LLM provider API directly.
- **Protocol logging** (`ctx.log()`, `ctx.info()`, and similar methods): Use the standard `logging` module.
- **Roots** (`ctx.session.list_roots()`): Get paths from tool parameters, resource URIs, or the server configuration.
- The 2026-07-28 revision has no SSE transport. Use Streamable HTTP.