Geologist report -> LLM call extracts minerals we are looking for (you inject a db query result on the user prompt), locations, assay mentions and risks into structured fields -> LLM call classifies evidence into positive indicators, negative indicators and unknowns -> LLM call estimates deposit potential and confidence -> database lookups inject regional ore demand, nearby deposits, infrastructure and historical yield data -> LLM call combines geological evidence with business context -> LLM call generates an investment recommendation and rationale.

That's what I mean by graph. Every step is a separate LLM call with a well-defined responsibility, consuming the output of the previous node. Each node can be tested, benchmarked, retrained, replaced, or monitored independently. Why would you use an agent here? You can cache every single system prompt on each call making your total token output much cheaper than having a full 'output' only token generation workflow which is what happens with agents.

There is nothing to discover. The workflow is already known. The company already knows how geologists evaluate prospects. The company already knows what data sources matter. The company already knows what the final output should look like. You don't want the model deciding which tools to call, which reasoning path to take, or which pieces of information are important every single run. You want the exact same process applied to every report so results are consistent, measurable, auditable and debuggable. My default is: One-shot prompt -> if not enough -> graph of LLM calls -> if not enough -> agent. A surprising amount of enterprise AI is really just: Unstructured input -> extraction -> classification -> enrichment from databases -> decision support. Not: Unstructured input -> autonomous agent spends 20 steps deciding what to do next.

Agents make sense when the workflow itself is unknown.

If the workflow is already understood, a graph is usually cheaper, more reliable, easier to evaluate, easier to debug, and less dependent on whatever synthetic "agentic" behaviors happened to get reinforced during post-training. I am sure people default to agents mostly because it's less engineering work than explicitly modeling the process.