We launched Infracost on HN five years ago (https://news.ycombinator.com/item?id=26064588) where our CLI generated cost estimates for infra-as-code, e.g. "this Terraform PR adds $400/mo". The idea was to shift cloud costs (FinOps) left, so engineers get visibility of costs before deployment and make better decisions.

Earlier this year we started seeing agent traffic in our logs and it looked like coding agents were calling our CLI. But that CLI wasn't designed with coding agents in mind. We went down a philosophical rabbit hole to see if a CLI is even needed anymore given that Claude, Copilot et al. already follow best practices. Ultimately we decided to create a new CLI from the ground up with coding agents in mind for two reasons:

1. We optimized the CLI for agent callers and cut Claude's output token usage by up to 79% and API cost by up to 67% versus a bare-Claude baseline. We wrote a blog documenting our lessons on optimizing user token usage when designing a CLI, e.g. using predicate flags so the agent doesn't compose jq | python | wc pipelines, output format that strips JSON's redundant field names. The blog is here: https://www.infracost.io/resources/blog/we-cut-claude-s-toke...

2. With cloud costs, precision matters. Telling a coding agent "make this Terraform cost-optimized" can be expensive and lossy. You burn tokens loading code and policy context into every conversation. Your agent could make up a price and you wouldn't know because it's difficult to verify that across the ~10M price points that AWS, Azure and Google have. The CLI runs static analysis on the code, uses the latest prices from cloud vendors, and passes that context to the coding agent.

So that's what we're launching today - Cost.dev: https://cost.dev/.

- It runs locally. Your code never leaves your machine, you get a fast feedback loop, and you're not burning API calls per character when you want to fetch prices.

- The CLI does the deterministic work. Fetching price points, scanning the code, validating fixes. The coding agent does the natural-language part. You don't have to trust the LLM to remember the rules, and can verify it called the right CLI command.

- It provides a consistent rule layer across every tool you use. Get cost estimates in your IDE and your coding agent with a single install. We support Claude Code, GitHub Copilot, Cursor, Windsurf, OpenAI Codex, Gemini CLI, as well as IDEs like VS Code and JetBrains

Before we keep building more in that direction, I want to sanity-check with HN: is "agents writing IaC in prod" actually a thing yet, or am I betting on a future that's still a year out? I know software developers are using coding agents heavily, but are platform/infra folks doing that for prod too? Also, if you have any feedback on Cost.dev, I'd love to hear it!

This is an interesting approach. I think people still underestimate how quickly token limits and context bloat become the bottleneck when you start running agents in production loops. Seems very relevant topic also given the environment. Will check it out

I don't know how they can justify 250 USD / month bill. let alone 1000 USD / month.

why would anyone need 10,000 runs a month? do people modify their infrastructure 10,000 times a month?

Not really seeing the point I just use openrouter if I'm penny pinching

The interesting bit is making cloud cost a first-class constraint for the agent loop, not just a post-hoc report. I'd be curious how you handle confidence/uncertainty in estimates, since a wrong cheap-looking recommendation can be worse than no estimate in infra PRs.

The useful split here seems to be: let the CLI do price lookup and validation, and let the agent decide which diff to make. The thing I’d watch is how visible the source of the estimate is in review — if a PR says “saved $X”, reviewers need to see which prices/rules produced that number.

The 79% / 67% reduction generalizes broader than IaC. Any CLI agents shell out to (curl, jq, grep, kubectl, gh, psql) burns the same token tax — verbose JSON, free-form text output, agent-composed pipelines. A predicate-flag + compact-output redesign would land on all of those.

  Direct answer to your question: agents-writing-IaC-in-prod is rare today but not zero. I see more "agent reviews the IaC PR a human wrote", which Cost.dev sounds well-suited to since verification runs locally and the agent only consumes the result. Even if the prod-IaC path takes another year, the design pattern earns its keep on every agent-shellout you already do. One question: does the CLI surface its cache state to the agent, or does each invocation start fresh Repeated price-fetches across a single agent run would be the obvious next-tier savings.