Files
agent-framework/python/samples/02-agents/tools/dynamic_tool_exposure.py
Eduard van Valkenburg 49a6e433a3 Python: progressive tool exposure via FunctionInvocationContext (#6233)
* Python: progressive tool exposure via FunctionInvocationContext

Add first-class progressive tool exposure to the Python core function-calling
loop. Tools can now add or remove real FunctionTool schemas at runtime via the
injected FunctionInvocationContext, taking effect on the next iteration of the
loop.

- FunctionInvocationContext gains a live `tools` list plus experimental
  `add_tools()` / `remove_tools()` helpers (feature: PROGRESSIVE_TOOLS).
- The function-calling loop establishes a run-local, normalized tools list and
  threads it into the context at both invocation paths so mutations propagate.
- Add a sample (dynamic_tool_exposure.py) and a tools samples README, including
  a note that CodeAct providers (Monty/Hyperlight) use their own provider-level
  tool management instead.

Supersedes #3877.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Validate non-negative input in dynamic_tool_exposure sample tools

Address review feedback: factorial and fibonacci now return an error
message for negative n instead of producing incorrect results.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Make add_tools atomic and surface swallowed function errors

Address review feedback on progressive tool exposure:

- add_tools now validates the full batch against a throwaway copy before
  committing, so a duplicate-name clash partway through a sequence leaves
  the live tool list unchanged (all-or-nothing).
- _auto_invoke_function now logs a warning (with traceback) when a tool
  raises, so contract errors such as a duplicate-name ValueError from
  add_tools are debuggable without enabling include_detailed_errors.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Avoid retaining tracebacks when logging swallowed function errors

Logging with exc_info=exc fed the exception traceback to the logging
machinery, whose frame references created reference cycles collected
lazily by the cyclic GC. On Windows that could drop a hyperlight
WasmSandbox on a non-owning thread ("unsendable, dropped on another
thread"), crashing the xdist worker. Log a pre-formatted message with
the exception repr instead, so no traceback object is retained.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* added missing decorator

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-06-03 09:01:07 +00:00

80 lines
2.9 KiB
Python

# Copyright (c) Microsoft. All rights reserved.
import asyncio
from typing import Annotated
from agent_framework import Agent, FunctionInvocationContext, tool
from agent_framework.openai import OpenAIChatClient
from dotenv import load_dotenv
from pydantic import Field
# Load environment variables from .env file
load_dotenv()
"""
Dynamic Tool Exposure (Progressive Tool Loading) Example
This example demonstrates "progressive tool exposure": a tool that adds more tools to
the agent at runtime, in the same run, via ``FunctionInvocationContext``.
Frontloading a model with hundreds of tools hurts tool-selection accuracy, bloats
context, and raises cost. Instead, you can start with a small set of "loader" tools and
let the model pull in additional tools on demand. Tools added with ``ctx.add_tools(...)``
(or removed with ``ctx.remove_tools(...)``) become available to the model on the next
iteration of the function-calling loop.
"""
# These math tools are not registered on the agent up front. They are added on demand by
# the ``load_math_tools`` tool below, and only then become callable by the model.
@tool(approval_mode="never_require")
def factorial(n: Annotated[int, Field(description="A non-negative integer.")]) -> str:
"""Compute the factorial of n."""
if n < 0:
return "Error: n must be a non-negative integer."
result = 1
for value in range(2, n + 1):
result *= value
return f"{n}! = {result}"
@tool(approval_mode="never_require")
def fibonacci(n: Annotated[int, Field(description="The 0-based index in the Fibonacci sequence.")]) -> str:
"""Compute the n-th Fibonacci number."""
if n < 0:
return "Error: n must be a non-negative integer."
a, b = 0, 1
for _ in range(n):
a, b = b, a + b
return f"fib({n}) = {a}"
# The only tool the agent starts with. When called, it exposes the math tools above so the
# model can use them on the next turn. Note the ``ctx`` parameter is injected by the
# framework and is not visible to the model.
@tool(approval_mode="never_require")
def load_math_tools(ctx: FunctionInvocationContext) -> str:
"""Load additional math tools (factorial, fibonacci) so they can be used."""
ctx.add_tools([factorial, fibonacci])
return "Loaded math tools: factorial, fibonacci. You can now call them."
async def main() -> None:
agent = Agent(
client=OpenAIChatClient(),
name="MathAgent",
instructions=(
"You are a math assistant. If you need math capabilities that are not yet "
"available, call load_math_tools first, then use the newly available tools."
),
tools=[load_math_tools],
)
# The agent starts with only ``load_math_tools``. To answer the question it must first
# load the math tools, then call ``factorial`` on the next iteration.
print(f"Agent: {await agent.run('What is 5 factorial?')}")
if __name__ == "__main__":
asyncio.run(main())