Agent evaluation and assurance
Why AI pilots never reach production, and what it takes to get one through the gate.
Agent evaluation and assurance is the discipline of proving an agentic system works well enough to deploy, and continuing to prove it once deployed: offline evaluation against a ground-truth set, trajectory scoring of the steps an agent takes rather than only its final answer, online monitoring, and release gates that can actually block a deploy. It is the single most common reason for AI pilots that never reach production. An organisation stuck in pilot usually has a system everybody believes works and no evidence anybody senior is willing to sign, and the gap is between a system that is watched and a system that is measured: monitoring tells you it is running, evaluation tells you whether it is right.
This is our approach, not a programme we have already run.
We have built evaluation and confidence scoring into the proofs of concept we have delivered, including validation and scoring of entity-resolution output on a live insurance engagement, and we have recommended against release at least once on every engagement we have run. What we have not yet done is stand up an enterprise-wide agent assurance function across a portfolio of systems, and what follows is the method we would bring to that, not a write-up of a programme we have already run.
The demand signal
Evaluation has stopped being a research topic and become infrastructure, which tells you where the expectation is heading. The UK AI Security Institute publishes an open-source evaluation framework, Inspect, built around three parts, datasets, solvers and scorers, and ships more than two hundred evaluations inside it. The published work on using a strong model as the judge reports over 80% agreement with human preference, about the level at which humans agree with each other, while naming the position, verbosity and self-enhancement biases you have to design around. The methods exist and are documented. What almost no organisation has is the same rigour pointed at its own workflows, and that gap is where the production decision stalls.
Why it stalls
5 failure modes we keep meeting
Pilot purgatory starts with a demonstration instead of a measurement
Someone senior watched it work and was impressed. That is not an evaluation, and it does not transfer. When the same system is asked to pass a production gate, there is no benchmark, no baseline and no agreed definition of good, so the gate becomes a negotiation rather than a test. Programmes stuck in pilot are almost always stuck precisely here: nobody doubts the system, and nobody can produce the evidence that would let a named person carry the risk of switching it on.
Only the final answer is scored
Agents take a sequence of steps: choosing tools, retrieving, deciding when to stop. A system can produce a correct answer through a process that is unsafe, expensive or unrepeatable. Scoring only the output hides that, and it is why systems that tested well fail differently in production.
Evaluation is owned by whoever built it
Self-marked homework. Where the build team owns the benchmark, the benchmark tends to describe what the system already does. Assurance needs a separate owner with the standing to block a release, which is an organisational question rather than a tooling one.
The pilot succeeded and then went nowhere, because nobody owned what came next
A successful pilot creates an orphan. The sponsor who funded an experiment is rarely the person who will carry a live system, its run cost, its incidents and its audit trail, and in most organisations nobody has been asked to. So a pilot succeeded and then went nowhere is usually not a technical verdict at all: it passed, and there was no named owner, no run budget and no slot in a delivery roadmap to receive it. We treat naming that receiver as part of the pilot rather than as a conversation for afterwards, because the answer changes what is worth building.
Nothing watches it after go-live
Model behaviour drifts, retrieval corpora change, and the input distribution moves. Without online monitoring against the same criteria used offline, degradation is discovered by users. Most programmes budget for pre-production evaluation and nothing for the two years afterwards.
How we approach it
6 moves, in order
- 01
Define what good means before anything is built
The same discipline as pricing an outcome in currency: if you cannot state the acceptance criteria, you cannot manage the work. We establish the ground-truth set and the pass thresholds with the business owner during design, and they become the release gate rather than a retrospective justification.
- 02
Measure confidence alongside accuracy, and derive it from provenance
Accuracy and confidence are the two measures we work to, and they answer different questions. On the insurance engagement, confidence was derived from which third-party source the data came from, combined with model certainty and a search-based cross-check, not from the model's self-reported score alone. Provenance-derived confidence is what makes routing defensible, because you can explain to the business owner why a given record was escalated.
- 03
Score the trajectory, not just the answer
Tool selection, retrieval quality, step count, cost and stopping behaviour are all measured, because a right answer reached the wrong way is a production incident waiting to happen. This mirrors how we treat delivery: flow and process are measured, not just the output at the end.
- 04
Put the gate in someone else's hands, and be willing to be that person
Assurance sits with a named owner outside the build team, with the authority to hold a release. It is the same accountability mapping as any other consequential decision: who decides, on what evidence, and who can overrule them. Part of what an external partner is for is being the person who can say no without worrying about their next promotion. We have recommended against release at least once on every engagement we have run, usually when a date was being defended rather than a readiness assessment.
- 05
Design the online case to match the offline one
The criteria that gate the release are the criteria monitored in production, so degradation is comparable rather than anecdotal. Alerting thresholds and the rollback decision are agreed before go-live, not during the first incident.
- 06
Make the evidence the artefact, and name the regime each artefact answers
Evaluation output is written for the audiences that will ask for it (risk, audit, and the regulator) rather than reconstructed under pressure later. If the evidence is a by-product of the process it is cheap, and if it is assembled retrospectively it is expensive and thin. For a UK insurer it is worth being specific about which regime each artefact is for, because that decides whether the same work gets done once or four times. The model and decision inventory, holding prompts, retrieval corpora, tool permissions and model versions as versioned artefacts with named owners, is what a model risk management framework asks for, and SS1/23 is the UK statement of that expectation for banks; insurers sit outside its formal scope and get asked about it anyway. Outcome measures emitted by the system as it runs, rather than reconstructed from logs a quarter later, are the Consumer Duty evidence for any workflow that touches a customer outcome, because that regime is written around acting to deliver good outcomes for retail customers and monitoring whether you did, rather than around any particular mechanism. Degradation monitoring alongside availability monitoring, and a fallback that is exercised rather than documented, are what an impact tolerance under the operational resilience regime actually rests on. And field-level provenance back to the source document or API is what the data quality expectations under Solvency II and Solvency UK come down to in practice for the actuarial function. One evaluation design can answer all four, but only if it is specified that way at the start.
Accuracy and confidence are the two measures we work to, and they answer different questions.
Keep the assurance function yourselves. Your second line and internal audit should own the gate, because the independence is the whole point of it and it is not something to buy from the firm that built the system. Use us for the build and for designing the evidence, so the ground-truth set, the trajectory scoring, the release criteria and the monitoring arrive as artefacts your own reviewers can hold us to rather than as a report about our work. And if what you actually need is the assurance function itself stood up rather than reasoned about, say so on the call: that is a real piece of work, it is not the piece we have done, and we will tell you whether we are the right firm for it.
Prefer to talk it through? Ask us on a discovery call →
Sources
Every source below was opened and read before it was attached. Where nothing survived that check, the claim on this page was softened rather than given a plausible-looking link.
UK AI Security Institute, Inspect: a framework for large language model evaluationsOpen-source, built by the UK AI Security Institute and Meridian Labs around datasets, solvers and scorers, with more than 200 evaluations included. Cited here as evidence of the shape a serious harness takes, not as a recommendation of a tool.Zheng et al., Judging LLM-as-a-Judge with MT-Bench and Chatbot Arena (2023)Source of the over 80% agreement figure, and of the position, verbosity and self-enhancement biases that make a model judge useful for triage and unsafe as a gate.FCA, the Consumer DutyThe Consumer Principle, the cross-cutting rules and the four outcomes, in the regulator's own words. Read it before accepting anyone's account of what the Duty asks of an agent.FCA, the Senior Managers and Certification RegimeThe regime behind the claim that accountability resolves to a named individual rather than to a system.The closest guides to this one
Nearest first, then the rest. Each one carries the same label: written from delivery, or the method we would bring. All 13 are on the hub.
AI governance and regulatory evidence
Building the evidence as a by-product of the work, rather than assembling it under deadline.
Our approachAgent identity and access
Agents are not users, and giving them a service account is how this goes wrong.
DeliveredDocument intelligence to business intelligence
Getting information out of PDFs and into something the business can decide with.
DeliveredAI-native SDLC and product delivery lifecycle
Changing how software gets specified, built and shipped once AI is in the room.
DeliveredTarget operating model for an AI-native organisation
What changes in structure, roles and decision rights once agents do a share of the work.
DeliveredVoice agents and conversation intelligence
Turning conversations into structured intelligence, and holding conversations that take real actions.
Or bring the problem to a call instead of reading three more of these.
Talk it throughTalk to us about agent evaluation and assurance.
A 30-minute call with James Rooney. We'll tell you honestly which parts of this we have done before and which we would be doing for the first time, and you'll leave with a rough scope either way.
most start with a fixed-price AI Readiness Audit · £44,000 · 4 weeks · working prototypes
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Questions this guide answers
Why do AI pilots never reach production?
Most commonly because there was never an evaluation, only a demonstration. Without a ground-truth set, agreed acceptance criteria and a release gate someone outside the build team can hold, the production decision becomes a negotiation with no evidence to settle it, and negotiations without evidence default to no. Three failures usually sit underneath: only the final answer was scored rather than the agent's trajectory, nothing was designed to monitor it after go-live, and no named person was asked to own the live system, its run cost and its incidents. Tenhaw pairs its builds with the receiving team for that reason. On a London specialty insurance proof of concept the client's engineer paired throughout and finished 70% confident they could run the process unaided.
What do we do when a pilot succeeded and then went nowhere?
Separate the two questions usually tangled together, whether it is good enough and who is receiving it. For the first, write the acceptance criteria the business owner would sign, then measure the existing system against them honestly, which is a two to three week piece of work that produces either a gate you can pass or a costed list of what is missing. For the second, name the person who will own the live system, its run budget and its incidents, and get them to agree the criteria before you re-test. Tenhaw names that receiver during the pilot rather than afterwards. Pilot purgatory is usually the second problem wearing the costume of the first, because teams keep improving a system nobody has been asked to take.
What is trajectory evaluation for AI agents?
Scoring the sequence of steps an agent takes (which tools it chose, what it retrieved, how many steps it used, what it cost, and when it decided to stop) rather than only the final output. It matters because an agent can produce a correct answer through a process that is unsafe, unrepeatable or prohibitively expensive, and output-only scoring makes that invisible until production.
Should a consultancy be willing to recommend against its own release?
Yes, and it is one of the more useful things an external partner is for. An internal team recommending a delay is arguing against a date their own management committed to, with their next promotion in the room. Tenhaw has recommended against release at least once on every engagement it has run, usually where a launch date was being defended rather than a readiness assessment being made. If a supplier has never told you not to ship, that is information about the supplier rather than about your programmes.
What do you measure when there is no ground truth?
Confidence derived from provenance rather than from the model's own certainty score. Tenhaw did exactly this on a live London specialty insurance engagement, scoring entity-resolution output by which third-party source the data came from, combined with model certainty and a search-based cross-check. Where the data came from gives you a defensible basis for routing before any labelled set exists, and it is explainable to the business owner, which a self-reported score is not. It is not a substitute for ground truth, and building one is still worth pushing for, but an organisation with no appetite for a labelling exercise is not stuck with nothing.
Who should own AI agent evaluation?
Someone outside the team that built the agent, with the standing to block a release. Tenhaw builds systems and designs the evidence but does not sell the gate. An engagement either side can end on thirty days' notice is the wrong permanent home for a decision your second line has to keep making. Where the build team owns the benchmark, the benchmark tends to describe what the system already does. This is an accountability question rather than a tooling one, and it is settled during operating-model design by mapping who decides, on what evidence, and who can overrule them.
What should we measure after an agent is live?
The same criteria that gated the release, so degradation is comparable rather than anecdotal, plus cost and latency distributions and the rate at which humans override the agent. Override rate is often the most useful early signal, because it moves before accuracy metrics do and it is measured on real decisions.
What does an evaluation harness for an agent actually consist of?
Four parts, and they are more ordinary than the phrase suggests. A dataset of real cases with the answer a qualified person would accept, held under version control and grown every time something goes wrong in production. A runner that executes the system against every case reproducibly, pinning the model version, the prompts, the retrieval corpus and the tool permissions, because a result you cannot reproduce is an anecdote. Scorers, which are a mixture of exact checks, rule-based assertions and, for open-ended output, a model acting as judge. And a report a non-engineer can read, showing the score against the threshold, what regressed since the last run, and what each run cost and how long it took. The UK AI Security Institute's open-source Inspect framework is built around exactly that shape, datasets, solvers and scorers, which is a reasonable sanity check on any design somebody presents to you. The part people underestimate is the dataset, because it is the only part that cannot be bought.
How do you build a ground-truth dataset for evaluating AI agents?
Start with real cases pulled from the workflow itself, each paired with the answer a qualified person would accept, and build the set with the business owner rather than leaving it to the engineers. Agree the pass thresholds during design, so the set becomes the release gate rather than a retrospective justification. Keep it under version control alongside the prompts, model versions and tool permissions it exercises, and grow it every time something goes wrong in production, because live failures are exactly the hard cases the original set was missing. Runners and scorers can be adopted from open-source frameworks; a labelled set that reflects your own workflow is the part you have to make yourselves.
What is the difference between monitoring and evaluating an AI agent?
Monitoring tells you the system is running. Evaluation tells you whether it is right. An agent can be fully available and quietly getting worse, because model behaviour drifts, retrieval corpora change and the input distribution moves, and none of that shows up on an uptime dashboard. The fix is to carry the offline evaluation criteria into production, running degradation monitoring alongside availability monitoring, with alerting thresholds and the rollback decision agreed before go-live rather than during the first incident. Most programmes budget for evaluation before release and nothing for the two years afterwards, which is why degradation is so often discovered by users rather than by the team that built the system.
How do we get started with agent evaluation and assurance?
Start during design rather than after a demonstration, because the whole value is in agreeing what good means before there is a system to defend. Tenhaw agrees the ground-truth set and the pass thresholds with the business owner during design so they become the release gate, and publishes the method for doing it in full, free to adopt without hiring anyone. The four parts are offline evaluation against that set, trajectory scoring of the steps the agent takes rather than only its final answer, online monitoring once it is live, and a gate someone outside the build team can hold. The runner, the scorers and the report are ordinary engineering once the definition is settled.
What happens if the agent fails its evaluation thresholds?
You get a specific, costed list of what is missing, which is a better position than a vague sense that the system is nearly there. A fail usually names a class of cases the system handles badly rather than condemning the idea, and those cases go into the dataset so the next run measures the fix rather than the impression. Hold the release, or ship the cases that pass and route the rest to a person until a later run clears them. That choice is a business decision rather than an engineering one. Failing a threshold and missing a date are different problems, and the second should never be solved by quietly moving the first.
Do we need all this for a low-risk internal AI tool?
Not the full apparatus. Scale it to consequence, so a tool that drafts text a person reads and edits before it goes anywhere does not need an independent gate owner or evidence mapped to four regulatory regimes. Tenhaw grades its own engineering rules the same way, publishing 72 of them on GitHub with an RFC 2119 severity on each rather than equal weight. The light tier still needs a definition of good agreed before anything is built, a small set of real cases with the answer a qualified person would accept, and something watching for degradation, because model behaviour drifts whether or not the use case is risky. The heavier version earns its cost when a decision touches a customer, money or a regulator.
Can one set of evaluation evidence answer more than one regulator?
Yes, if it is specified that way at the start; otherwise the same work gets done four times. Tenhaw specifies that mapping at the start, and the client owns the inventory, evidence and code from day one. For a UK insurer, one design can answer four regimes. A model and decision inventory holding prompts, corpora, tool permissions and model versions with named owners is what model risk management asks for, and SS1/23 states that expectation for UK banks; insurers sit outside its formal scope and are asked anyway. Outcome measures emitted as the system runs are the Consumer Duty evidence. Degradation monitoring with an exercised fallback is what an impact tolerance rests on, and field-level provenance to source is the Solvency II data quality expectation.
Does building an evaluation set slow the project down?
It moves the argument earlier, to where it is cheap. Tenhaw builds the ground-truth set inside a retainer month that carries a value target, and a month that moves no number the client agreed is reported back as a failed month, so the set is built on the delivery clock rather than beside it. The thresholds are agreed during design alongside acceptance criteria you would be writing anyway. If you cannot state what good looks like, you cannot manage the work. Skip it and the production decision becomes a negotiation with no evidence to settle it, which is where programmes lose quarters. After the first run the harness makes delivery quicker, because a change is scored against every case at once.
Do we need to re-run evaluation when the model version changes?
Yes, and it is one of the better arguments for having a harness at all. A run pins the model version alongside the prompts, the retrieval corpus and the tool permissions, so changing any of them gives you a different system and the previous result no longer describes it. Re-run the same dataset, compare against the same thresholds, and read what regressed since the last run. Providers update and retire versions on their own schedule rather than yours, which is why the re-run wants to be a routine job somebody owns rather than a project somebody funds.
What happens to the evaluation harness when the build team leaves?
It hands over with everything else. On a Tenhaw engagement the exit date is agreed at kickoff, the final sixty days of a build run as a documented handover taper, and recruiting your permanent team is a stated deliverable of the retainer engagements. The dataset, the runner, the scorers and the report sit under version control in your own repositories, and the criteria that gated the release are the ones already monitored in production, so there is nothing to rebuild. What matters more is that a named person has been asked to own the live system, its run cost and its incidents, because if nobody has, evaluation quietly stops when the project does. Naming that receiver belongs in the pilot rather than afterwards.
Can a non-technical risk team sign off an AI agent?
Yes, and designing for that is part of the work. What qualifies someone to hold a release gate is independence and the standing to say no, not the ability to read the code. What the team needs is evidence it can act on: the score against the agreed threshold, what regressed since the last run, and what each run cost and how long it took, written for the audience that will ask for it rather than reconstructed under pressure later. Agree the criteria with risk during design instead of presenting results afterwards, and name the regime each artefact answers, so they are checking evidence rather than translating it.