Merge pull request #48 from modelcontextprotocol/davidsp/example

Example server to expose a fetch tool

Author: dsp-ant

examples/README.md

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+# Python SDK Examples
+
+This folders aims to provide simple examples of using the Python SDK. Please refer to the
+[example-servers repository](https://github.com/modelcontextprotocol/example-servers)
+for real-world servers.

examples/servers/simple-prompt/.python-version

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+3.11

examples/servers/simple-prompt/README.md

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+# MCP Simple Prompt
+
+A simple MCP server that exposes a customizable prompt template with optional context and topic parameters.
+
+## Usage
+
+Start the server using either stdio (default) or SSE transport:
+
+```bash
+# Using stdio transport (default)
+mcp-simple-prompt
+
+# Using SSE transport on custom port
+mcp-simple-prompt --transport sse --port 8000
+```
+
+The server exposes a prompt named "simple" that accepts two optional arguments:
+
+- `context`: Additional context to consider
+- `topic`: Specific topic to focus on
+
+## Example
+
+Using the MCP client, you can retrieve the prompt like this:
+
+```python
+from mcp.client import ClientSession
+
+async with ClientSession() as session:
+    await session.initialize()
+
+    # List available prompts
+    prompts = await session.list_prompts()
+    print(prompts)
+
+    # Get the prompt with arguments
+    prompt = await session.get_prompt("simple", {
+        "context": "User is a software developer",
+        "topic": "Python async programming"
+    })
+    print(prompt)
+```

examples/servers/simple-prompt/mcp_simple_prompt/__init__.py

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+

examples/servers/simple-prompt/mcp_simple_prompt/__main__.py

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+import sys
+
+from server import main
+
+sys.exit(main())

examples/servers/simple-prompt/mcp_simple_prompt/server.py

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+import anyio
+import click
+import mcp.types as types
+from mcp.server import Server
+
+
+@click.group()
+def cli():
+    pass
+
+
+@cli.command()
+@click.option("--port", default=8000, help="Port to listen on for SSE")
+@click.option(
+    "--transport",
+    type=click.Choice(["stdio", "sse"]),
+    default="stdio",
+    help="Transport type",
+)
+def main(port: int, transport: str) -> int:
+    return anyio.run(_amain, port, transport)
+
+
+def create_messages(
+    context: str | None = None, topic: str | None = None
+) -> list[types.PromptMessage]:
+    """Create the messages for the prompt."""
+    messages = []
+
+    # Add context if provided
+    if context:
+        messages.append(
+            types.PromptMessage(
+                role="user",
+                content=types.TextContent(
+                    type="text", text=f"Here is some relevant context: {context}"
+                ),
+            )
+        )
+
+    # Add the main prompt
+    prompt = "Please help me with "
+    if topic:
+        prompt += f"the following topic: {topic}"
+    else:
+        prompt += "whatever questions I may have."
+
+    messages.append(
+        types.PromptMessage(
+            role="user", content=types.TextContent(type="text", text=prompt)
+        )
+    )
+
+    return messages
+
+
+async def _amain(port: int, transport: str) -> int:
+    app = Server("mcp-simple-prompt")
+
+    @app.list_prompts()
+    async def list_prompts() -> list[types.Prompt]:
+        return [
+            types.Prompt(
+                name="simple",
+                description="A simple prompt that can take optional context and topic "
+                           "arguments",
+                arguments=[
+                    types.PromptArgument(
+                        name="context",
+                        description="Additional context to consider",
+                        required=False,
+                    ),
+                    types.PromptArgument(
+                        name="topic",
+                        description="Specific topic to focus on",
+                        required=False,
+                    ),
+                ],
+            )
+        ]
+
+    @app.get_prompt()
+    async def get_prompt(
+        name: str, arguments: dict[str, str] | None = None
+    ) -> types.GetPromptResult:
+        if name != "simple":
+            raise ValueError(f"Unknown prompt: {name}")
+
+        if arguments is None:
+            arguments = {}
+
+        return types.GetPromptResult(
+            messages=create_messages(
+                context=arguments.get("context"), topic=arguments.get("topic")
+            ),
+            description="A simple prompt with optional context and topic arguments",
+        )
+
+    if transport == "sse":
+        from mcp.server.sse import SseServerTransport
+        from starlette.applications import Starlette
+        from starlette.routing import Route
+
+        sse = SseServerTransport("/messages")
+
+        async def handle_sse(scope, receive, send):
+            async with sse.connect_sse(scope, receive, send) as streams:
+                await app.run(
+                    streams[0], streams[1], app.create_initialization_options()
+                )
+
+        async def handle_messages(scope, receive, send):
+            await sse.handle_post_message(scope, receive, send)
+
+        starlette_app = Starlette(
+            debug=True,
+            routes=[
+                Route("/sse", endpoint=handle_sse),
+                Route("/messages", endpoint=handle_messages, methods=["POST"]),
+            ],
+        )
+
+        import uvicorn
+
+        uvicorn.run(starlette_app, host="0.0.0.0", port=port)
+    else:
+        from mcp.server.stdio import stdio_server
+
+        async with stdio_server() as streams:
+            await app.run(streams[0], streams[1], app.create_initialization_options())
+
+    return 0

examples/servers/simple-prompt/pyproject.toml

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+[project]
+name = "mcp-simple-prompt"
+version = "0.1.0"
+description = "A simple MCP server exposing a customizable prompt"
+readme = "README.md"
+requires-python = ">=3.10"
+authors = [{ name = "Anthropic, PBC." }]
+maintainers = [
+    { name = "David Soria Parra", email = "davidsp@anthropic.com" },
+    { name = "Justin Spahr-Summers", email = "justin@anthropic.com" },
+]
+keywords = ["mcp", "llm", "automation", "web", "fetch"]
+license = { text = "MIT" }
+classifiers = [
+    "Development Status :: 4 - Beta",
+    "Intended Audience :: Developers",
+    "License :: OSI Approved :: MIT License",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.10",
+]
+dependencies = ["anyio>=4.6.2.post1", "click>=8.1.7", "httpx>=0.27.2", "mcp"]
+
+[project.scripts]
+mcp-simple-prompt = "mcp_simple_prompt.server:main"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["mcp_simple_prompt"]
+
+[tool.pyright]
+include = ["mcp_simple_prompt"]
+venvPath = "."
+venv = ".venv"
+
+[tool.ruff.lint]
+select = ["E", "F", "I"]
+ignore = []
+
+[tool.ruff]
+line-length = 88
+target-version = "py310"
+
+[tool.uv]
+dev-dependencies = ["pyright>=1.1.378", "pytest>=8.3.3", "ruff>=0.6.9"]