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Give an agent capabilities beyond conversation: define function tools it can call, connect MCP servers to expose external tools, and handle DTMF and voicemail on telephony calls.

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function_tool

Expose a function to the model as a callable tool. Works bare or with arguments. The name, description and parameter schema are read off the function itself — its __name__, the prose above its Args: block, and its type hints — so a well-written docstring is what the model sees.
Methods on an Agent subclass are registered automatically; tools defined elsewhere go in Agent(tools=[...]).
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Optional[Callable]
The function, when used bare.
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Optional[str]
Override the exposed name. Everything else the model is told comes off the function itself, so this is the only knob.
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The function, marked as a tool.

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MCPServerStdio

A local MCP server, run as a subprocess and spoken to over stdio.

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Fields

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str
required
The program to run, e.g. sys.executable.
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List[str]
default:"…"
Its arguments — typically the server script.
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Optional[Dict[str, str]]
Environment for the child. None inherits this process’s, which is usually what you want: the server needs the same API keys you already have.
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Optional[Union[str, Path]]
Directory to run it in.
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float
default:"5.0"
Seconds to wait for the connection and for each tool call. The vendor’s default is 5, which is tight for a server that starts an interpreter; its own examples pass 30.
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str
default:"stdio"
Always stdio. Set for you — it is what tells the SDK which transport to connect with.

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MCPServerHTTP

A remote MCP server, reached over HTTP.

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Fields

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str
required
The server’s URL.
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Optional[Dict[str, str]]
Sent with every request — an API key usually lives here. Read in this process, so the credential stays with you.
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float
default:"10.0"
Seconds to wait for the connection.
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float
default:"300.0"
Seconds a quiet stream may stay open. Long by default: an MCP server that has nothing to say is not broken.
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float
default:"5.0"
Seconds to wait for the session, and for each tool call.
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str
default:"http"
Always http. Set for you.