All roles

We build the eval suite you would hire a prompt and evaluation engineer for.

Bigcircle does not place engineers. Making quality measurable means versioned prompts, an eval set pulled from real traffic, metrics that match the task, a gate on the release, and red-team cases next to the happy path. We deliver that as a studio engagement through our LLM evaluation service.

In short

Bigcircle does not place prompt or evaluation engineers. Our team builds the suite that makes quality a number a release can fail on: versioned prompts, regression suites, LLM-as-judge beside human review, and red-team cases. On our trademark drafting system, every draft passes a legal-integrity harness on six axes before it reaches the attorney.

Key facts

Definition

A prompt and evaluation engineer on a Bigcircle team turns quality into a number a release can fail: versioned prompts, regression suites, and a red-team case beside the happy path.

How Bigcircle does it

  1. Bigcircle vets its own team starting from a suite the engineer built.
  2. The exercise worsens an answer the suite still passes, and Bigcircle watches the engineer show which check should have caught the failure.
  3. On a Bigcircle build prompts are versioned, an LLM judge sits beside human review, and a feeling that the answer is better does not ship.

Comparison

A feeling that the answer improved cannot block a merge, while the evaluation engineer on a Bigcircle team ships a suite that can.

At a glance

Versioned prompts and an eval suite that can block a merge, built by our team.

See how Bigcircle turns a quality feeling into a suite that can block a merge, what it has built for legal drafting and coaching, and the three ways to buy it.

Who this is for
Teams that set out to hire a prompt & evaluation engineer to build a system, and would rather buy the working system.
Topics
  • LLM-as-judge
  • Custom metrics
  • Golden sets
  • Versioning
  • Templating
  • Structured outputs

What the work involves in production.

  • Designing and versioning prompts that stay reliable in production
  • Evaluation suites that catch regressions automatically
  • LLM-as-judge alongside human review
  • Quality tracked as a metric instead of a feeling
  • Red-team cases for safety and edge cases
  • Accuracy, tone, and format tuned together

Systems we deliver in this area.

Evaluation and regression-testing harnesses
Prompt libraries and versioning systems
Quality dashboards for AI features
Red-team and safety test suites
A/B frameworks for model and prompt changes

Tools they reach for in production.

Eval
LLM-as-judgeCustom metricsGolden sets
Prompt
VersioningTemplatingStructured outputs
Tools
LangfusePromptfooTracingRagasLangSmithBraintrust
Stack
PythonClaude / GPT

Who builds it: Bigcircle's core team scopes the system and leads the build. Every engineer on that team cleared five stages of vetting and stays on one product.

Three ways to buy the eval suite.

Every engagement is a working system, built in your repositories under your IP by the team that scoped it. The three differ only in how much of the delivery we run.

We finish it

Production hardening

Your team built something that works in the demo and stalls on real inputs. We define what good means and build the eval set, route models for cost and latency, lock down the data path, and put a safety net under it before it takes traffic.

Best when you have a prototype that will not cross into production.

We build it

Fixed-scope build

You bring the problem and we deliver the working AI system. Discovery, build, evals and deployment sit under one point of accountability, against a scope and price agreed before we start.

Best when the problem is clear and you want the result, not a team to manage.

We run it

Studio-led programme

A studio team of engineers and QA, led by our founder as your fractional CTO and architect, owns delivery on your AI roadmap. We run the build rhythm and make the hard technical calls; you bring the product context.

Best when you have a roadmap and no senior AI team to run it.

Choosing between the three is the engagement guide.

Five stages.
The top 3% remain.

Every engineer on the core team that leads your system cleared these before joining. Each stage asks whether they can keep AI running once real customers are using it.

400 applicants

3%of applicants join
the team

What removes them

  1. We start with something they built

    100% → 20%

    One real system, pressed hard. How much traffic did it take? What broke first? Who got the call when it did?

  2. We break something and watch them fix it

    20% → 9%

    A working system with a bug hidden inside it. Anyone can build a demo in a weekend. Fixing code you have never seen is the actual job.

  3. How will you know it is working?

    9% → 5%

    Before they write anything, they have to tell us how they would test it, and what they would do when it gets an answer wrong.

  4. Make it fast without running up the bill

    5% → 4%

    We give them a speed target and a budget, then ask them to explain the tradeoffs they made to hit both.

  5. It is late and the AI got it wrong

    4% → 3%

    What do you do first? How do you find out what happened, undo it, and explain it to the customer in plain words?

Common questions

  • Can I hire a prompt or evaluation engineer from Bigcircle?

    No. Bigcircle does not place engineers or do staff augmentation. Bigcircle builds the eval suite as a studio engagement through its LLM evaluation and AI observability services, with versioned prompts, a gate on the release, and red-team cases beside the happy path.

  • What evals has Bigcircle built?

    Bigcircle built a 0 to 10 legal-integrity harness on six axes that scores every trademark draft before an attorney sees it. On RepliCoach, Bigcircle's own sales roleplay coach, the score comes from a versioned rubric and the model writes only the qualitative read, so a model upgrade cannot shift historical comparisons.

  • How does a Bigcircle eval engagement start?

    Bigcircle starts with a conversation about what good output means for your system. You get a written scope covering what Bigcircle would build, in what order, and what it depends on from your side, then choose production hardening for a prototype you already have, a fixed-scope build at an agreed scope and price, or a studio-led programme led by our founder as fractional CTO. For evals, the work runs through pulling a set from real traffic, picking metrics that match the task, gating the release, and keeping the suite alive. The work happens in your repositories, and you own the code.

  • Who at Bigcircle builds the eval suite?

    Every engineer on Bigcircle's core team cleared five stages before joining, and the top 3% of applicants remain. Vetting starts from a system they already built, then breaks something and watches them fix it. For eval work the exercise makes an answer worse while the suite still passes, and the engineer has to show which check should have caught it. They also say how they would know it is working, how they would make it fast without running up the bill, and what they do first when it is late and the AI got it wrong. They lead client builds as a team.

Tell us what the hire was meant to build.

Bigcircle does not place engineers. Describe the system and what is in the way, and an engineer replies within two hours on weekdays. A written scope follows within a week.

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