TL;DR: LLM costs rise when retries, tool calls, agent loops, and larger context windows compound inside production workflows, and Braintrust argues that trace-level observability is what reveals the spans driving spend rather than hiding them inside aggregate dashboards. The practical shift is to pair cost attribution with prompt experimentation, model comparison, and eval-backed release control so teams can cut spend without degrading output quality.
NHIMG editorial — based on content published by Braintrust: How AI observability helps lower LLM cost at scale
By the numbers:
- Prompt optimization can often reduce input token cost by 20 to 40 percent without requiring a model change.
Questions worth separating out
Q: How should teams reduce LLM costs without breaking production quality?
A: Start with request-level tracing so you know which prompts, models, retrieval steps, or tool calls drive cost.
Q: Why do agentic AI workflows make cost governance harder?
A: Agentic workflows multiply calls across retrieval, tools, retries, and intermediate reasoning, so the final answer cost is much higher than a single model request suggests.
Q: What do security teams get wrong about AI cost control?
A: They often treat cost as a finance-only issue and overlook the identity layer that drives usage.
Practitioner guidance
- Instrument trace-level cost attribution Capture token usage, estimated cost, and latency on every span so expensive retrieval steps, retries, and agent loops are visible in context.
- Review the highest-cost workflow spans first Start optimisation with the span that dominates the trace, then decide whether to shorten context, tighten retrieval, or replace the model used for that step.
- Use evals to gate cheaper prompts and models Convert production traces into repeatable eval cases and block release if the lower-cost variant reduces quality below the agreed threshold.
What's in the full article
Braintrust's full article covers the operational detail this post intentionally leaves for the source:
- Inline cost tracking examples showing how every span rolls up into a full trace cost.
- Prompt experimentation workflows for comparing token usage, cost, and quality side by side.
- Model comparison and eval-backed release control for selecting the cheapest acceptable model.
- Practical trace and timeline views that highlight expensive retrieval, retry, and tool-call patterns.
👉 Read Braintrust's guide to lowering LLM cost with AI observability →
LLM cost observability: what it means for AI teams?
Explore further
Observability debt is now a governance problem for AI operations. When teams can only see aggregate spend, they lose the ability to distinguish routine usage from pathological execution paths. In practice, that means cost, quality, and control drift together. For AI programmes that rely on delegated tools and service credentials, the lack of trace-level visibility also obscures where non-human identity activity is creating risk.
A question worth separating out:
Q: How can organisations govern AI systems that use tools and secrets?
A: Treat the AI workflow as a non-human identity with delegated access. Define which service accounts, tokens, and API keys it may use, limit that access to the smallest possible scope, and review the runtime paths that consume those credentials. If the workflow can call tools, it needs identity governance as much as any other privileged system.
👉 Read our full editorial: AI observability lowers LLM spend by exposing costly workflow spans