virtual or real. The former refers to a simulated environment that allows the model to interact with a digital
representation of the tool, while a real environment involves actual interaction with the physical tool. Virtual
environments have the advantage of being easily accessible and replicable, allowing for more cost-effective
training for models. However, virtual environments may not fully replicate the complexities of the real-world
environment, leading to overﬁtting and poor generalization (Hansen et al., 2021). On the other hand, real
environments provide a more realistic context but may be more challenging to access and involve greater costs.
Controller. The controller C serves as the “brain” for tool learning framework and is typically modeled using
a foundation model. The purpose of the controller C is to provide a feasible and precise plan for using tools
to fulﬁll the user’s request. To this end, C should understand user intent as well as the relationship between
Tool Learning with Foundation Models