Use an agent when the path needs to change
A fixed sequence of predictable steps often belongs in a workflow. An agent earns its complexity when it must choose tools or revise its plan from new evidence. Start with a narrow task and compare it with a simpler implementation before adding more agents.
Make tool boundaries explicit
Give each tool a validated input schema, scoped permissions, and a clear failure result. Keep read access separate from actions that change business records. Bound execution time and cost. Retried writes need protection against duplicate actions.
Verify the result outside the model
Test the final business outcome as well as individual model answers. Use traces to reconstruct tool calls and decisions. Keep cases for missing data, conflicting evidence, unavailable tools, and attempted instruction injection. A convincing explanation is not a substitute for a verified result.