Repository navigation
Python: @kernel_function mutates shared Annotated metadata dicts (description lost after first use) #14441
Description
Description
@kernel_function's _parse_parameter() calls meta.pop("description") on dict metadata inside typing.Annotated, mutating the caller's dict. Reusing one shared metadata dict across kernel functions silently strips the parameter description from every function after the first, and leaves the user's dict empty.
Reproduction
from typing import Annotated
from semantic_kernel.functions.kernel_function_decorator import kernel_function
from semantic_kernel.functions import KernelFunctionFromMethod
shared = {"description": "the answer count"}
@kernel_function
def a(x: Annotated[int, shared]) -> int: ...
@kernel_function
def b(y: Annotated[int, shared]) -> int: ...
KernelFunctionFromMethod(a, "a").metadata.parameters[0].description # 'the answer count'
KernelFunctionFromMethod(b, "b").metadata.parameters[0].description # None <-- lost
shared # {} <-- caller's dict mutatedExpected behavior
Decoration never mutates caller-owned metadata; both functions see the description.
Environment
semantic-kernel python main (ca40aa72), Python 3.12
Activity
nslabhwan commentedon Sep 16, 2026
I reproduced this on current main.
_parse_parameter()mutates caller-ownedAnnotateddict metadata viameta.pop("description"), so reusing the same metadata dict loses the description after the first decoration. I'm taking this issue with a focused fix that copies the metadata dict before parsing and a regression test covering reuse across two@kernel_functiondecorators. Targeted function tests and Ruff checks are passing; I'll open a small PR.