What is an agent harness?
An agent harness is the loop around a model that plans work, edits files, runs commands and checks the result. You may also see it called a coding harness or an LLM harness. Codex, Claude Code and Pi are well-known examples.
Agent harness vs model API
A model API gives your application access to a model: you send input and receive a response, which may include a request to call a tool. An agent harness manages the work around those calls. It supplies context, runs tools, reads their results, and continues through the task. For a CSV cleanup, that means reading the file, running a cleanup script, checking the output, and writing the result. The model is one part of that process; the harness connects the steps.
How HarnessAny uses an agent harness
HarnessAny started by running agent harnesses in the cloud, so a single request could become finished files. Today, HarnessAny focuses on giving you the newest AI models in one place.
FAQ
How is an agent harness different from a model API?
A model API gives your application access to a model: you send input and receive a response, which may include a request to call a tool. An agent harness manages the work around those calls. It supplies context, runs tools, reads their results, and continues through the task. For a CSV cleanup, that means reading the file, running a cleanup script, checking the output, and writing the result. The model is one part of that process; the harness connects the steps.
Which agent harnesses are common?
Codex, Claude Code and Pi are widely used agent harnesses. Each pairs a model with tools for reading files, running commands and checking results.