Tool-Use

A production prompt is not a clever sentence. It is one component in a system that includes model configuration, trusted instructions, untrusted input, tools, validators, retries, monitoring, and human review. The useful unit of design is therefore a testable contract: what the model may read; what it must produce; which tools it may request; which constraints are enforced outside the model; how failures are detected; and which evidence determines whether a change is safe to release. Prompt wording still matters, but wording alone cannot guarantee factuality, valid data, authorisation, or reliable execution. Those properties require controls around the model. ...

An LLM becomes an agent when its outputs can change an environment: querying a database, editing a record, sending a message, running code, or asking a person for approval. The model remains important, but the production system around it determines whether those actions are valid, authorised, repeatable, and observable. This distinction matters. A capable model inside a weak control loop can execute the wrong tool, repeat an irreversible action after a timeout, or follow malicious instructions hidden in retrieved content. A dependable agent therefore needs more than prompting. It needs an explicit action interface, an execution policy, state management, safety boundaries, and evaluation over complete trajectories. ...