chore: import upstream snapshot with attribution
This commit is contained in:
@@ -0,0 +1,634 @@
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<!--
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name: 'Data: Tool use reference — Python'
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description: Python tool use reference including tool runner, manual agentic loop, code execution, and structured outputs
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ccVersion: 2.1.203
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-->
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# Tool Use — Python
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For conceptual overview (tool definitions, tool choice, tips), see [shared/tool-use-concepts.md](../../shared/tool-use-concepts.md).
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## Tool Runner (Recommended)
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**Beta:** The tool runner is in beta in the Python SDK.
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Use the `@beta_tool` decorator to define tools as typed functions, then pass them to `client.beta.messages.tool_runner()`:
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```python
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import anthropic
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from anthropic import beta_tool
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client = anthropic.Anthropic()
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@beta_tool
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def get_weather(location: str, unit: str = "celsius") -> str:
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"""Get current weather for a location.
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Args:
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location: City and state, e.g., San Francisco, CA.
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unit: Temperature unit, either "celsius" or "fahrenheit".
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"""
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# Your implementation here
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return f"72°F and sunny in {location}"
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# The tool runner handles the agentic loop automatically
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runner = client.beta.messages.tool_runner(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=[get_weather],
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messages=[{"role": "user", "content": "What's the weather in Paris?"}],
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)
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# Each iteration yields a BetaMessage; iteration stops when Claude is done
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for message in runner:
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print(message)
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```
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For async usage, use `@beta_async_tool` with `async def` functions.
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**Key benefits of the tool runner:**
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- No manual loop — the SDK handles calling tools and feeding results back
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- Type-safe tool inputs via decorators
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- Tool schemas are generated automatically from function signatures
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- Iteration stops automatically when Claude has no more tool calls
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### Server tools with the tool runner
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The runner's `tools` list accepts raw server-tool definitions (`web_search_20260209`, `web_fetch_20260209`, code execution) alongside decorated tools — pass the literal tool dict; server tools run on Anthropic's servers, so there is no function to implement.
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**Caution — the runner does not auto-resume `pause_turn` (as of `anthropic` 0.116.0).** A long-running server-tool turn can stop with `stop_reason: "pause_turn"`. The runner only continues after a client tool produces a result, so a paused turn ends the loop and is returned as the final message — no error, no warning, just a silently truncated answer. Unlike the TypeScript runner, the Python runner cannot be resumed mid-loop: it exits unconditionally when no client tool ran, and `runner.append_messages(...)` does not prevent the exit. To handle `pause_turn`, mirror the conversation history as you iterate, then restart the runner with the paused turn appended:
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```python
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messages = [{"role": "user", "content": user_input}]
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max_restarts = 5 # cap pause_turn restarts, mirroring max_continuations advice
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restarts = 0
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while True:
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runner = client.beta.messages.tool_runner(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools, # may mix @beta_tool functions and server-tool definitions
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messages=messages,
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)
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last = None
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for message in runner:
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last = message
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# Mirror the history — the runner keeps its own copy and does not expose it
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messages.append({"role": "assistant", "content": message.content})
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tool_response = runner.generate_tool_call_response() # cached; tools still run once
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if tool_response is not None:
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messages.append(tool_response)
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if last is None or last.stop_reason != "pause_turn":
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break
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restarts += 1
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if restarts > max_restarts:
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raise RuntimeError("giving up: turn still paused after max_restarts")
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# Paused mid-turn: `messages` already ends with the paused assistant
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# turn, so the next runner resumes it
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```
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Alternatively, use the manual loop below, which handles `pause_turn` explicitly.
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---
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## MCP Tool Conversion Helpers
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**Beta.** Convert [MCP (Model Context Protocol)](https://modelcontextprotocol.io/) tools, prompts, and resources to Anthropic API types for use with the tool runner. Requires `pip install anthropic[mcp]` (Python 3.10+).
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> **Note:** The Claude API also supports an `mcp_servers` parameter that lets Claude connect directly to remote MCP servers. Use these helpers instead when you need local MCP servers, prompts, resources, or more control over the MCP connection.
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### MCP Tools with Tool Runner
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```python
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from anthropic import AsyncAnthropic
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from anthropic.lib.tools.mcp import async_mcp_tool
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from mcp import ClientSession
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from mcp.client.stdio import stdio_client, StdioServerParameters
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client = AsyncAnthropic()
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async with stdio_client(StdioServerParameters(command="mcp-server")) as (read, write):
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async with ClientSession(read, write) as mcp_client:
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await mcp_client.initialize()
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tools_result = await mcp_client.list_tools()
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# tool_runner is sync — returns the runner, not a coroutine
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runner = client.beta.messages.tool_runner(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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messages=[{"role": "user", "content": "Use the available tools"}],
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tools=[async_mcp_tool(t, mcp_client) for t in tools_result.tools],
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)
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async for message in runner:
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print(message)
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```
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For sync usage, use `mcp_tool` instead of `async_mcp_tool`.
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### MCP Prompts
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```python
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from anthropic.lib.tools.mcp import mcp_message
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prompt = await mcp_client.get_prompt(name="my-prompt")
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response = await client.beta.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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messages=[mcp_message(m) for m in prompt.messages],
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)
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```
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### MCP Resources as Content
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```python
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from anthropic.lib.tools.mcp import mcp_resource_to_content
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resource = await mcp_client.read_resource(uri="file:///path/to/doc.txt")
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response = await client.beta.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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messages=[{
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"role": "user",
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"content": [
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mcp_resource_to_content(resource),
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{"type": "text", "text": "Summarize this document"},
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],
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}],
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)
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```
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### Upload MCP Resources as Files
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```python
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from anthropic.lib.tools.mcp import mcp_resource_to_file
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resource = await mcp_client.read_resource(uri="file:///path/to/data.json")
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uploaded = await client.beta.files.upload(file=mcp_resource_to_file(resource))
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```
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Conversion functions raise `UnsupportedMCPValueError` if an MCP value cannot be converted (e.g., unsupported content types like audio, unsupported MIME types).
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---
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## Manual Agentic Loop
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Prefer the tool runner above. Drop to a manual loop only when you need control the runner does not expose (e.g., a custom transport, request shapes the SDK cannot build, or avoiding a beta dependency — the runner is beta). Human-in-the-loop approval does *not* require a manual loop — gate inside the tool function (return a "user declined" result) or inspect pending `tool_use` blocks in the `for message in runner:` body and call `runner.set_messages_params()`.
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If you do need a manual loop:
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```python
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import anthropic
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client = anthropic.Anthropic()
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tools = [...] # Your tool definitions
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messages = [{"role": "user", "content": user_input}]
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# Agentic loop: keep going until Claude stops calling tools
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while True:
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response = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools,
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messages=messages
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)
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# If Claude is done (no more tool calls), break
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if response.stop_reason == "end_turn":
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break
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# Server-side tool hit iteration limit; re-send to continue
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if response.stop_reason == "pause_turn":
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messages = [
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{"role": "user", "content": user_input},
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{"role": "assistant", "content": response.content},
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]
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continue
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# Extract tool use blocks from the response
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tool_use_blocks = [b for b in response.content if b.type == "tool_use"]
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# Append assistant's response (including tool_use blocks)
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messages.append({"role": "assistant", "content": response.content})
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# Execute each tool and collect results
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tool_results = []
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for tool in tool_use_blocks:
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result = execute_tool(tool.name, tool.input) # Your implementation
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tool_results.append({
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"type": "tool_result",
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"tool_use_id": tool.id, # Must match the tool_use block's id
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"content": result
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})
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# Append tool results as a user message
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messages.append({"role": "user", "content": tool_results})
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# Final response text
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final_text = next(b.text for b in response.content if b.type == "text")
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```
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---
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## Handling Tool Results
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```python
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response = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools,
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messages=[{"role": "user", "content": "What's the weather in Paris?"}]
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)
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for block in response.content:
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if block.type == "tool_use":
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tool_name = block.name
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tool_input = block.input
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tool_use_id = block.id
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result = execute_tool(tool_name, tool_input)
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followup = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools,
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messages=[
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{"role": "user", "content": "What's the weather in Paris?"},
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{"role": "assistant", "content": response.content},
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{
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"role": "user",
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"content": [{
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"type": "tool_result",
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"tool_use_id": tool_use_id,
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"content": result
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}]
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}
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]
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)
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```
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---
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## Multiple Tool Calls
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```python
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tool_results = []
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for block in response.content:
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if block.type == "tool_use":
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result = execute_tool(block.name, block.input)
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tool_results.append({
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"type": "tool_result",
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"tool_use_id": block.id,
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"content": result
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})
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# Send all results back at once
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if tool_results:
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followup = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools,
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messages=[
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*previous_messages,
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{"role": "assistant", "content": response.content},
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{"role": "user", "content": tool_results}
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]
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)
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```
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---
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## Error Handling in Tool Results
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```python
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tool_result = {
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"type": "tool_result",
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"tool_use_id": tool_use_id,
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"content": "Error: Location 'xyz' not found. Please provide a valid city name.",
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"is_error": True
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}
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```
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---
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## Tool Choice
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```python
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response = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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tools=tools,
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tool_choice={"type": "tool", "name": "get_weather"}, # Force specific tool
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messages=[{"role": "user", "content": "What's the weather in Paris?"}]
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)
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```
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---
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## Code Execution
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### Basic Usage
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```python
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import anthropic
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client = anthropic.Anthropic()
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response = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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messages=[{
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"role": "user",
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"content": "Calculate the mean and standard deviation of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"
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}],
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tools=[{
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"type": "code_execution_20260120",
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"name": "code_execution"
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}]
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)
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for block in response.content:
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if block.type == "text":
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print(block.text)
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elif block.type == "bash_code_execution_tool_result":
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print(f"stdout: {block.content.stdout}")
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```
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### Upload Files for Analysis
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```python
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# 1. Upload a file
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uploaded = client.beta.files.upload(file=open("sales_data.csv", "rb"))
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# 2. Pass to code execution via container_upload block
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# Code execution is GA; Files API is still beta (pass via extra_headers)
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response = client.messages.create(
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model="{{OPUS_ID}}",
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max_tokens=16000,
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extra_headers={"anthropic-beta": "files-api-2025-04-14"},
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messages=[{
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"role": "user",
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"content": [
|
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{"type": "text", "text": "Analyze this sales data. Show trends and create a visualization."},
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{"type": "container_upload", "file_id": uploaded.id}
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]
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||||
}],
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tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
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||||
)
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||||
```
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|
||||
### Retrieve Generated Files
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||||
|
||||
```python
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import os
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||||
OUTPUT_DIR = "./claude_outputs"
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os.makedirs(OUTPUT_DIR, exist_ok=True)
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||||
|
||||
for block in response.content:
|
||||
if block.type == "bash_code_execution_tool_result":
|
||||
result = block.content
|
||||
if result.type == "bash_code_execution_result" and result.content:
|
||||
for file_ref in result.content:
|
||||
if file_ref.type == "bash_code_execution_output":
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||||
metadata = client.beta.files.retrieve_metadata(file_ref.file_id)
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||||
file_content = client.beta.files.download(file_ref.file_id)
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||||
# Use basename to prevent path traversal; validate result
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safe_name = os.path.basename(metadata.filename)
|
||||
if not safe_name or safe_name in (".", ".."):
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print(f"Skipping invalid filename: {metadata.filename}")
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||||
continue
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||||
output_path = os.path.join(OUTPUT_DIR, safe_name)
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||||
file_content.write_to_file(output_path)
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||||
print(f"Saved: {output_path}")
|
||||
```
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||||
|
||||
### Container Reuse
|
||||
|
||||
```python
|
||||
# First request: set up environment
|
||||
response1 = client.messages.create(
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||||
model="{{OPUS_ID}}",
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||||
max_tokens=16000,
|
||||
messages=[{"role": "user", "content": "Install tabulate and create data.json with sample data"}],
|
||||
tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
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||||
)
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||||
|
||||
# Get container ID from response
|
||||
container_id = response1.container.id
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||||
|
||||
# Second request: reuse the same container
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||||
response2 = client.messages.create(
|
||||
container=container_id,
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{"role": "user", "content": "Read data.json and display as a formatted table"}],
|
||||
tools=[{"type": "code_execution_20260120", "name": "code_execution"}]
|
||||
)
|
||||
```
|
||||
|
||||
### Response Structure
|
||||
|
||||
```python
|
||||
for block in response.content:
|
||||
if block.type == "text":
|
||||
print(block.text) # Claude's explanation
|
||||
elif block.type == "server_tool_use":
|
||||
print(f"Running: {block.name} - {block.input}") # What Claude is doing
|
||||
elif block.type == "bash_code_execution_tool_result":
|
||||
result = block.content
|
||||
if result.type == "bash_code_execution_result":
|
||||
if result.return_code == 0:
|
||||
print(f"Output: {result.stdout}")
|
||||
else:
|
||||
print(f"Error: {result.stderr}")
|
||||
else:
|
||||
print(f"Tool error: {result.error_code}")
|
||||
elif block.type == "text_editor_code_execution_tool_result":
|
||||
print(f"File operation: {block.content}")
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Memory Tool
|
||||
|
||||
### Basic Usage
|
||||
|
||||
```python
|
||||
import anthropic
|
||||
|
||||
client = anthropic.Anthropic()
|
||||
|
||||
response = client.messages.create(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{"role": "user", "content": "Remember that my preferred language is Python."}],
|
||||
tools=[{"type": "memory_20250818", "name": "memory"}],
|
||||
)
|
||||
```
|
||||
|
||||
### SDK Memory Helper
|
||||
|
||||
Subclass `BetaAbstractMemoryTool`:
|
||||
|
||||
```python
|
||||
from anthropic.lib.tools import BetaAbstractMemoryTool
|
||||
|
||||
class MyMemoryTool(BetaAbstractMemoryTool):
|
||||
def view(self, command): ...
|
||||
def create(self, command): ...
|
||||
def str_replace(self, command): ...
|
||||
def insert(self, command): ...
|
||||
def delete(self, command): ...
|
||||
def rename(self, command): ...
|
||||
|
||||
memory = MyMemoryTool()
|
||||
|
||||
# Use with tool runner
|
||||
runner = client.beta.messages.tool_runner(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
tools=[memory],
|
||||
messages=[{"role": "user", "content": "Remember my preferences"}],
|
||||
)
|
||||
|
||||
for message in runner:
|
||||
print(message)
|
||||
```
|
||||
|
||||
For full implementation examples, use WebFetch:
|
||||
|
||||
- `https://github.com/anthropics/anthropic-sdk-python/blob/main/examples/memory/basic.py`
|
||||
|
||||
---
|
||||
|
||||
## Structured Outputs
|
||||
|
||||
### JSON Outputs (Pydantic — Recommended)
|
||||
|
||||
```python
|
||||
from pydantic import BaseModel
|
||||
from typing import List
|
||||
import anthropic
|
||||
|
||||
class ContactInfo(BaseModel):
|
||||
name: str
|
||||
email: str
|
||||
plan: str
|
||||
interests: List[str]
|
||||
demo_requested: bool
|
||||
|
||||
client = anthropic.Anthropic()
|
||||
|
||||
response = client.messages.parse(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{
|
||||
"role": "user",
|
||||
"content": "Extract: Jane Doe (jane@co.com) wants Enterprise, interested in API and SDKs, wants a demo."
|
||||
}],
|
||||
output_format=ContactInfo,
|
||||
)
|
||||
|
||||
# response.parsed_output is a validated ContactInfo instance
|
||||
contact = response.parsed_output
|
||||
print(contact.name) # "Jane Doe"
|
||||
print(contact.interests) # ["API", "SDKs"]
|
||||
```
|
||||
|
||||
### Raw Schema
|
||||
|
||||
```python
|
||||
response = client.messages.create(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{
|
||||
"role": "user",
|
||||
"content": "Extract info: John Smith (john@example.com) wants the Enterprise plan."
|
||||
}],
|
||||
output_config={
|
||||
"format": {
|
||||
"type": "json_schema",
|
||||
"schema": {
|
||||
"type": "object",
|
||||
"properties": {
|
||||
"name": {"type": "string"},
|
||||
"email": {"type": "string"},
|
||||
"plan": {"type": "string"},
|
||||
"demo_requested": {"type": "boolean"}
|
||||
},
|
||||
"required": ["name", "email", "plan", "demo_requested"],
|
||||
"additionalProperties": False
|
||||
}
|
||||
}
|
||||
}
|
||||
)
|
||||
|
||||
import json
|
||||
# output_config.format guarantees the first block is text with valid JSON
|
||||
text = next(b.text for b in response.content if b.type == "text")
|
||||
data = json.loads(text)
|
||||
```
|
||||
|
||||
### Strict Tool Use
|
||||
|
||||
```python
|
||||
response = client.messages.create(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{"role": "user", "content": "Book a flight to Tokyo for 2 passengers on March 15"}],
|
||||
tools=[{
|
||||
"name": "book_flight",
|
||||
"description": "Book a flight to a destination",
|
||||
"strict": True,
|
||||
"input_schema": {
|
||||
"type": "object",
|
||||
"properties": {
|
||||
"destination": {"type": "string"},
|
||||
"date": {"type": "string", "format": "date"},
|
||||
"passengers": {"type": "integer", "enum": [1, 2, 3, 4, 5, 6, 7, 8]}
|
||||
},
|
||||
"required": ["destination", "date", "passengers"],
|
||||
"additionalProperties": False
|
||||
}
|
||||
}]
|
||||
)
|
||||
```
|
||||
|
||||
### Using Both Together
|
||||
|
||||
```python
|
||||
response = client.messages.create(
|
||||
model="{{OPUS_ID}}",
|
||||
max_tokens=16000,
|
||||
messages=[{"role": "user", "content": "Plan a trip to Paris next month"}],
|
||||
output_config={
|
||||
"format": {
|
||||
"type": "json_schema",
|
||||
"schema": {
|
||||
"type": "object",
|
||||
"properties": {
|
||||
"summary": {"type": "string"},
|
||||
"next_steps": {"type": "array", "items": {"type": "string"}}
|
||||
},
|
||||
"required": ["summary", "next_steps"],
|
||||
"additionalProperties": False
|
||||
}
|
||||
}
|
||||
},
|
||||
tools=[{
|
||||
"name": "search_flights",
|
||||
"description": "Search for available flights",
|
||||
"strict": True,
|
||||
"input_schema": {
|
||||
"type": "object",
|
||||
"properties": {
|
||||
"destination": {"type": "string"},
|
||||
"date": {"type": "string", "format": "date"}
|
||||
},
|
||||
"required": ["destination", "date"],
|
||||
"additionalProperties": False
|
||||
}
|
||||
}]
|
||||
)
|
||||
```
|
||||
Reference in New Issue
Block a user