A new blog post from Hugging Face zeroes in on the vocabulary used to describe AI agents, specifically the terms "harness" and "scaffold." The author contends that these words are often used interchangeably, which muddies the design and communication of agent systems. Getting the definitions right, the post suggests, is not pedantry but a practical necessity for building reliable agents.
The post distinguishes between the harness—the outer control loop that runs an agent—and the scaffold, which typically refers to the surrounding code and tools that support the model's reasoning. By separating these concepts, developers can more clearly discuss where responsibilities lie and where failures might occur. The author argues that shared terminology helps teams coordinate and avoids subtle misunderstandings that can derail projects.
Ultimately, the blog is a call for clearer language in the fast-moving agent space. As more developers build on top of large language models, a common vocabulary becomes a foundation for collaboration. The post does not introduce new benchmarks or tools, but it makes a case for slowing down to define terms before scaling up the engineering.