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Add reconnect example for async tools
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‎examples/clients/async-reconnect-client/README.md‎

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# Async Reconnect Client Example
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A demonstration of how to use the MCP Python SDK to call async tools and handle operation tokens for resuming long-running operations.
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## Features
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- Async tool invocation with operation tokens
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- Operation status polling and result retrieval
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- Support for resuming operations with existing tokens
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## Installation
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```bash
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cd examples/clients/async-reconnect-client
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uv sync --reinstall
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```
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## Usage
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### 1. Start an MCP server with async tools
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```bash
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# Example with simple-tool-async server
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cd examples/servers/simple-tool-async
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uv run mcp-simple-tool-async --transport streamable-http --port 8000
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```
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### 2. Run the client
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```bash
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# Connect to default endpoint
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uv run mcp-async-reconnect-client
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# Connect to custom endpoint
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uv run mcp-async-reconnect-client --endpoint http://localhost:3001/mcp
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# Resume with existing operation token
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uv run mcp-async-reconnect-client --token your-operation-token-here
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```
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## Example
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The client will call the `fetch_website` async tool and demonstrate:
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1. Starting an async operation and receiving an operation token
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2. Polling the operation status until completion
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3. Retrieving the final result when the operation completes
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```bash
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$ uv run mcp-async-reconnect-client
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Calling async tool...
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Operation started with token: abc123...
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Status: submitted
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Status: working
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Status: completed
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Result: <html>...</html>
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```
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The client can be terminated during polling and resumed with the returned token, demonstrating how reconnection is supported:
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```bash
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$ uv run mcp-async-reconnect-client
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Calling async tool...
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Operation started with token: abc123...
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Status: working
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^C
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Aborted!
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$ uv run mcp-async-reconnect-client --token=abc123...
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Calling async tool...
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Status: completed
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Result: <html>...</html>
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```
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## Configuration
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- `--endpoint` - MCP server endpoint (default: http://127.0.0.1:8000/mcp)
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- `--token` - Operation token to resume with (optional)
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This example showcases the async tool capabilities introduced in MCP protocol version "next", allowing for long-running operations that can be resumed even if the client disconnects.

‎examples/clients/async-reconnect-client/mcp_async_reconnect_client/__init__.py‎

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‎examples/clients/async-reconnect-client/mcp_async_reconnect_client/client.py‎

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import asyncio
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import click
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from mcp import ClientSession, types
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from mcp.client.streamable_http import streamablehttp_client
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async def call_async_tool(session: ClientSession, token: str | None):
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"""Demonstrate calling an async tool."""
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print("Calling async tool...")
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if not token:
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result = await session.call_tool("fetch_website", arguments={"url": "https://modelcontextprotocol.io"})
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assert result.operation
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token = result.operation.token
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print(f"Operation started with token: {token}")
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# Poll for completion
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while True:
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status = await session.get_operation_status(token)
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print(f"Status: {status.status}")
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if status.status == "completed":
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final_result = await session.get_operation_result(token)
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for content in final_result.result.content:
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if isinstance(content, types.TextContent):
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print(f"Result: {content.text}")
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break
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elif status.status == "failed":
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print(f"Operation failed: {status.error}")
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break
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await asyncio.sleep(0.5)
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async def run_session(endpoint: str, token: str | None):
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async with streamablehttp_client(endpoint) as (read, write, _):
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async with ClientSession(read, write, protocol_version="next") as session:
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await session.initialize()
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await call_async_tool(session, token)
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@click.command()
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@click.option("--endpoint", default="http://127.0.0.1:8000/mcp", help="Endpoint to connect to")
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@click.option("--token", default=None, help="Operation token to resume with")
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def main(endpoint: str, token: str | None):
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asyncio.run(run_session(endpoint, token))

‎examples/clients/async-reconnect-client/pyproject.toml‎

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[project]
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name = "mcp-async-reconnect-client"
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version = "0.1.0"
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description = "A client for the MCP simple-tool-async server that supports reconnection"
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readme = "README.md"
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requires-python = ">=3.10"
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authors = [{ name = "Anthropic" }]
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keywords = ["mcp", "client", "async"]
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license = { text = "MIT" }
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classifiers = [
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"Development Status :: 4 - Beta",
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"Intended Audience :: Developers",
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"License :: OSI Approved :: MIT License",
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"Programming Language :: Python :: 3",
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"Programming Language :: Python :: 3.10",
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]
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dependencies = ["click>=8.2.0", "mcp>=1.0.0"]
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[project.scripts]
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mcp-async-reconnect-client = "mcp_async_reconnect_client.client:main"
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[build-system]
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requires = ["hatchling"]
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build-backend = "hatchling.build"
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[tool.hatch.build.targets.wheel]
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packages = ["mcp_async_reconnect_client"]
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[tool.pyright]
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include = ["mcp_async_reconnect_client"]
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venvPath = "."
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venv = ".venv"
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[tool.ruff.lint]
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select = ["E", "F", "I"]
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ignore = []
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[tool.ruff]
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line-length = 120
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target-version = "py310"
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[tool.uv]
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dev-dependencies = ["pyright>=1.1.379", "pytest>=8.3.3", "ruff>=0.6.9"]
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[tool.uv.sources]
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mcp = { path = "../../../" }
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[[tool.uv.index]]
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url = "https://pypi.org/simple"

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