AI Engineer World's Fair 2025
From Copilot to Colleague: Building Trustworthy Productivity Agents for High-Stakes Work
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From Copilot to Colleague: Building Trustworthy Agents for High-Stakes Work
Productive agents need more than good answers: they need domain tools, inspectable sources, evaluation that accounts for human variability, and agency matched to the risk of the work.
From a talk by Joel Hron
When helpful answers become consequential work
What changes when an assistant stops helping a professional make a decision and starts making judgments on that professional’s behalf? Early assistants were built around helpfulness, with accuracy and citations supporting that goal. The next expectation is more demanding: produce the work itself.
In law, tax, global trade, risk and fraud investigations, that shift changes the consequences of an error. A useful suggestion and a completed piece of professional work carry different expectations. Productivity requires trust in the output and in the process that produced it. This is the problem Joel Hron brings to agent design at Thomson Reuters.
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The assets behind a professional agent
Thomson Reuters approaches this problem with longstanding relationships in the professions it serves. Hron reports that its customers include 97% of the top 100 US law firms, 99% of the Fortune 100, and the top 100 US CPA firms. Those relationships create expectations about how professional software should behave, as well as access to the expertise needed to evaluate it.
Hron reports 4,500 domain experts and more than 1.5 terabytes of proprietary content underpinning the company’s software. He also tentatively describes Thomson Reuters as the world’s largest employer of lawyers. The relevant asset is the combination: a collection of professional source material and people who can judge whether a system uses it correctly.
Hron describes more than $3 billion in acquisitions over the preceding couple of years, an applied research lab with slightly more than 200 scientists and engineers, and annual capital spending above $200 million on AI product development. These are his descriptions of company scale and spending, rather than measures of agent performance.
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Agency has four adjustable dimensions
Hron introduces the shift through his paraphrase of Y Combinator’s summer 2025 Requests for Startups: build law firms of agents rather than agentic tools for law firms. The distinction is between supporting someone who produces a result and taking responsibility for producing that result.
Agency is a spectrum, not a binary property. Exploratory work may benefit from giving a system more freedom. A workflow that demands precision and an expected sequence of operations may require less. The useful design question is how much agency each part of the experience should have, given the task and the user’s tolerance for risk.
Hron separates that decision into four dimensions:
- Autonomy: Move from a discrete instruction, such as summarizing a document, to a workflow in which the assistant plans, executes and replans in response to what it observes.
- Context: Move from the model’s parametric knowledge to retrieval-augmented generation, then to multiple sources. With both a controlled collection and the web available, the system must judge which source is appropriate in context. At the speculative upper end, it might modify the sources or their schemas to support future questions.
- Memory: Move from retrieving context for one request to sharing information across execution steps and retaining it across user sessions.
- Coordination: Move from an assistant completing a task on its own to delegating to tools and collaborating with other agents.
These dimensions can be adjusted separately. Giving an agent persistent memory does not, by itself, require giving it unrestricted control over the workflow.
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Evaluation has variability on both sides
Trust often comes from predictability: provide a familiar input and receive an expected outcome. Users bring that expectation to AI systems, and so do the internal subject-matter experts who evaluate them. Probabilistic behavior makes that expectation difficult to meet, but the evaluator is not a perfectly stable reference either.
Hron reports ten-plus-percent swings in assessed accuracy when the same trained legal experts reevaluate the same question-response data a week later. This is an internal observation about variation in human judgments, not a measured model regression; he does not specify whether the change is relative or in percentage points. If the reference judgment moves, an apparent improvement or decline becomes harder to interpret. Repeated evaluation is also expensive when weekly development cycles require time from lawyers or tax professionals.
Greater agency adds another evaluation problem: the final answer is only the end of a trajectory. Source attribution becomes harder to preserve, and a poor result may reflect drift earlier in the workflow. Finding where the agent went off course—and why—requires inspecting more than the output. Even the guardrails used to constrain the system require deep domain knowledge.
Thomson Reuters uses detailed rubrics alongside preference judgments, with different roles for each:
| Evaluation signal | Role |
|---|---|
| Detailed rubrics | Improve particular components |
| Preference judgments | Assess overall progress |
The rubrics make local improvement tractable. Preference provides a broader signal about whether the resulting experience is getting better or worse.
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Expose established domain logic as tools
Existing applications can constrain a new product, but they also contain carefully developed domain logic that users already expect. Early assistant development often started separately, leaving much of that logic and infrastructure behind. Agents create another option: decompose the application into capabilities the agent can call as tools.
A specialized application then becomes part of the agent’s working environment. Its domain logic need not be recreated in model-generated reasoning. The slide connects domain logic, user context and human expertise with agent tools, integrated experiences and alignment of AI judgments. What once looked like legacy baggage can become a foundation for the new system.
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Build enough to observe the whole workflow
An isolated component can be the wrong unit of product learning. Hron describes teams overemphasizing the minimal part of an MVP and spending time optimizing what appeared to be the smallest valuable piece of the system. They could not yet see whether that piece was the actual obstacle to completing the work.
Running the whole workflow changed that picture. Some weaknesses needed engineering attention; others could be recovered from through the agent’s subsequent actions. Observe complete execution before deciding which component deserves optimization. The team’s shift was to build the whole workflow first and learn from its behavior, rather than treating improvement of an isolated component as sufficient evidence of product progress.
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Tax preparation: extract, calculate, validate, revisit
The tax demonstration starts with explicitly fake data and a familiar professional task: receive source documents, extract their contents, map the information into tax software and generate a return. Inputs include forms such as a W-2 or 1099. The demonstrated outcome is return preparation; it does not establish autonomous filing.
The workflow divides interpretation from specialized calculation:
- Extract document data. AI reads the values from the source forms.
- Map values to tax-engine fields. The system considers tax rules and conditions to determine whether a value applies and which line or field should receive it.
- Generate the return through the tax engine. The existing engine provides the calculation capability used by the agent.
- Inspect validation errors. A validation engine built into the tax engine checks the work and exposes errors.
- Return to the source documents. The agent looks for additional information when needed and resolves issues to finish the workflow.
The validation result is therefore an input to further work. The agent can use a domain system’s feedback to decide what information it needs next, rather than stopping after its first extraction and mapping pass.
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Legal research: from tool calls to cited synthesis
The second demonstration follows legal research for litigation preparation. It applies deep research to the company’s proprietary content, using capabilities from an existing litigation-research product: search for documents, fetch them, compare citations across cases and validate citations within cases. The sources span case law, statutes, regulations, legal know-how, articles, blogs and licensed material.
The visible Research Trajectory Explorer exposes the work beneath the product interface. An expanded fetch_document entry shows its input and returned court-opinion text. This is an intermediate retrieval step: it makes part of the research path inspectable, rather than showing only a polished answer.
As research proceeds, the model writes notes about what it is finding and learning. At the end, it reconciles those notes into a final report. The report links to actual cases and statutes within the product, and visible flags indicate risks associated with the cited material. The result connects synthesis back to legal authorities that a professional can inspect.
Together, the tax and legal demonstrations show why application decomposition and complete workflows matter. In tax, the agent uses calculation and validation capabilities; in legal research, it uses retrieval and citation capabilities. In both cases, established software participates in producing the result rather than merely supplying background text.
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Build differentiation around what the organization knows
The design strategy begins with the whole problem and adjusts agency to the risk of the use case and the user’s tolerance. Existing systems supply reusable capabilities, while subject-matter experts remain central to evaluating the work. These decisions connect product scope, architecture and human judgment: none can be settled solely by choosing a model.
Hron’s closing question is organizational as much as technical: which assets do you have that others do not? For Thomson Reuters, he points back to its domain experts and proprietary content. The opportunity is to turn those assets into distinctive product behavior—what the agent can do, which sources it can consult, and how its work can be judged.
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Security posture remains a separate deployment question
The audience question brings the discussion to adoption in defense or finance. Invoking CISA and government requirements, the questioner asks about the architecture’s cybersecurity posture, including LLM firewalls, guardrails, automated vulnerability scanning and SCM security posture management. These are requests for concrete controls, beyond the correctness and usefulness of the agent’s output.
Hron’s response stays at the level of standards and supporting documentation. He points to online technical documentation and describes a focus on standards such as FedRAMP when working with government; the response does not establish a particular product’s authorization. He also says several products comply with a recent ISO standard, without naming the standard or products, and emphasizes adapting as requirements evolve. The exchange leaves the deployment topology and implementation of the requested security controls unspecified.
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Resources
Further reading
A conversation with Joel Hron and David Wong about professional AI, domain expertise and customer needs.
The March 2025 announcement explains the AI management-system certification and names the covered Westlaw solutions.
Updates since the talk
A July 2025 introduction to tax agents that combine document processing, tax software and professional review.
A later account of CoCounsel Legal’s architecture, source access and evolution beyond predefined workflows.
Read the complete timestamped transcript
- 0:00
[upbeat music] [audience applauding]
- 0:19
So, uh, nice to meet you all. Thank you for having me. Um, you know, probably two, two and a half years ago, like many other companies out there, you know, we sort of started on this journey of, of building assistants.
- 0:31
And sort of the North Star that we had when we were building these assistants were that they were helpful, you know? And obviously, we wanted them to be as accurate as they could, and to reference citations when they could, and these kinds of things.
- 0:45
But at the end of the day, we wanted it to be helpful. And I think over the last two, two and a half years, and certainly, like within the last six months, like, that North Star has shifted from helpfulness to productive.
- 0:58
Like, like, we're not asking assistants to just be helpful anymore. We're asking them to actually, like, produce output, um, to, to make judgments and decisions on behalf of users.
- 1:09
And, uh, in, in the environments that we work in, in, in the law, tax, global trade, um, uh, risk and, and fraud investigations, like, the risks of being wrong are, are not particularly acceptable to our end user.
- 1:26
So doing that in those kinds of environments I think is somewhat unique and, and that's hopefully what we'll talk about today. A little context on Thomson Reuters as a, as a company.
- 1:37
Um, may be, may be different from many of you who, like, started a company and grew to tens of thousands of users in a couple weeks. We've, we've been around for over 100 years.
- 1:47
Um, we, like I said, rep- represent legal, tax, compliance, audit, risk. Uh, 97% of the top 100 US law firms are customers of ours. Um, 99% of the Fortune 100, uh, corporate customers of ours, uh, and the top 100 US, uh, CPA firms.
- 2:07
So we've had a long standing and a, and a, a pretty significant presence in many of these industries for a lar- long time, and really what, what it underpins that is our domain expertise and content.
- 2:20
So we have 4,500, uh, domain experts. I think we're the, the, the highest employer of lawyers in the world, as an example. And, you know, our proprietary content really underpins most of our software products, uh, that our customers use, and it's north of one and a half terabytes of, of proprietary content across those industries that, you know,
- 2:42
we serve to our customers through, through our software. Uh, you know, we're heavily acquisitive as a company. We've spent over $3 billion in acquisitions over the last couple of years.
- 2:53
Uh, we have an applied research lab with, uh, a little more than 200 scientists and engineers, uh, that work closely with our development teams. And, uh, as a company, we spend north of $200 million a year, uh, in capital on AI product development.
- 3:09
So it's a little background on who we are as TR. Um, so I'll switch gears, just talk about maybe ground us in the evolution of, of where AI has been and where it's come.
- 3:19
So I think this quote from Y Combinator in their summer 2025 sort of request for startups is pretty good grounding. And they said, you know, paraphrase a little bit here, but this is pretty much what they said.
- 3:32
They said, "Don't build agentic tools for law firms. Build law firms of agents." And I think that, like, signifies, like, the profound shift of, like, moving from helpfulness to productive.
- 3:43
Like, we're asking AI systems to now produce output and produce judgments and decisions, uh, and not just be helpful to people who are doing those kinds of tasks. Um, and, and that's the shift that we're experiencing with agentic AI.
- 3:59
I think, you know, what, what does agentic AI actually mean? Uh, I think we've been talking about this a little bit. I think we, we like to define it more as a spectrum.
- 4:09
Uh, it is not that this system is agentic or it is not, but in fact, um, these are dials that can be used to, uh, to, to sort of tune what the experience and, and how much agency the experience has for the user, depending on the use case.
- 4:29
There's some use cases where it's very exploratory, and you may want to dial these agency dials far up. Uh, there are other situations where there's a high degree of precision and, and there's sort of an expectation of certainty, uh, around how a, a certain workflow might need to be executed, and you may not want to dial the
- 4:49
agency up in those situations. And so we view these things as levers that we are able to kind of move up and down, depending what our users are willing to tolerate in terms of the, the risk of the situation that they, they may be dealing with.
- 5:04
And each of these dials you can think of, um, somewhat discreetly. So, like, the autonomy dial, this is the ability of an AI assistant to go do a discrete task, like summarize this document,
- 5:18
all the way down the spectrum to, uh, very variable, kind of self-evolving workflows, where the AI assistant is planning its own work, it's executing its own work, and it's replanning that work along the way based on what it is, it is observing or learning along the path.
- 5:36
Context is also a dial. Like, the, the sort of first, most simple examples were, like, using parametric knowledge of the models directly, and then RAG became a big thing, and we, we added one kn- uh, knowledge source.
- 5:48
We added another knowledge source. And then the models then need to sort of rationalize between, let's say, a controlled knowledge source and the web. And it needs to use both of these sources of information, and it needs to understand- Which one is better under which context, all the way to perhaps the models even permuting the data sources
- 6:07
themselves and updating not just the, the data, but perhaps the schemas of the data, uh, to make, to make better use of them for future types of, of questions that may get asked.
- 6:18
Memory is another dial. Like, you know, the, the earliest systems of RAG that we had were somewhat stateless. Uh, they retrieved the context at the point in time. Uh, and what we're seeing now is that memory needs to be shared, uh, th-throughout the workflow.
- 6:34
Uh, it may need to be shared across a series of execution steps in that workflow, and it may need, and likely does need, to be persistent across many sessions of users.
- 6:46
And so these are also dials that we can use from a, from a memory perspective. And then lastly, coordination. Um, coordination is the idea of, uh, uh, an LLM or an AI assistant just, uh, atomically executing a task, like I mentioned, summarizing documents, uh, to delegation to tools, uh, to, to full agent systems, uh, collaborating with each
- 7:08
other. So again, just to sum-- Like, these are levers that we view, uh, the ability to kinda pull up and down depending on the type of use case and, and what, what sort of agency we wanna give the system.
- 7:21
So I'll switch gears and just share kinda some lessons that we've learned along the way from the last two and a half years of, of building this. And, and some of this may be obvious, some of it maybe not.
- 7:31
Um, the first is gonna be on evals. Evals is maybe the hardest thing that we do, and I think for our users, um,
- 7:40
one of the things that is m-most challenging is that, like, to build trust in the system, they almost expect a determinism. Like, like, b-sort of by definition, trust comes through like, you know, having certainty and, and an expected outcome when you give a certain input, and that is just not the way that these systems work.
- 7:59
And, uh, that has been, I think, a really challenging bar, not just to climb for our users, but also for our own internal SMEs who evaluate these systems alongside of us.
- 8:11
Um, what we see in our own development is that even with highly trained domain experts in legal, I could give the same set of data, like question response, to the same people a week later, and we see ten plus percent swings in accuracy by the same people and the same questions.
- 8:30
And so their own judgments are highly variable as well, and it's, it's quite difficult to, to sort of, uh, understand whether you're climbing that hill or not. Uh, the, the other challenge is that, you know, it's quite expensive.
- 8:44
These are highly trained, uh, lawyers or tax professionals, whatever it may be. Uh, and if you're iterating on a system every week, like, you know, it's quite expensive to, to, to leverage this amount of, of, uh, human judgment.
- 8:58
Um, we see these challenges sort of amplified by agentic systems. Some of the challenges a-are that, uh, referencing to source material, which is probably one of the most important things for any of our applications, becomes more challenging as you start to build these systems with higher levels of agency.
- 9:18
We see these agents sort of drift and, and identifying why they have drift, drifted and where they have drifted along the trajectory becomes more challenging. And building the guardrail systems themselves require, you know, a deep level of expert knowledge.
- 9:35
I think, you know, as we've approached our evals, like, we have really focused on, uh, developing pretty rigorous rubrics for how we eval. But at the end of the day, I do think we need sorta north stars that guide us, and in many ways, like, we really look at preference at the end of the day to really
- 9:53
drive u-an understanding of are we getting better or are we getting worse? But we do have, like, deeper levels of rubric that we use to sorta hill climb on certain components of the system.
- 10:04
The other thing we've learned is that our legacy applications are, you know, in, in many ways, they're a handicap, to be honest with you. But in a lot of ways, I think they're really enabling, and I'll show you a couple demos of that in, in just a minute.
- 10:16
But we've-- have a hundred plus years of building software systems that have highly tuned domain logic, uh, and, and our users expect this sort of logic in the way that they work.
- 10:26
And, you know, early on in the age of building assistants, you know, we were kinda just starting over. We were leaving all that behind us and, and building something new, somewhat from scratch.
- 10:36
But what agents have allowed us to do is to really decompose these legacy applications and decompose the components of them as tools that agents can now use. And so we're, we're finding new ways to leverage a lot of these legacy applications and infrastructure that, um, you know, previously we, we might have thought of as baggage, but I
- 10:56
think are really unique assets for us, uh, to build on going forward. And then the last thing I would say as a learning is, uh, which may be somewhat non-intuitive, is, uh, you know, this whole idea of MVPs, which sorta like centers in everybody's mind when they're building a new product.
- 11:14
I think, I think in many times we've over-indexed on the word minimal. Like... And we've sorta like chased rabbit holes in development, trying to optimize what we thought of as like sort of the smallest, most valuable piece of, you know, code that we could build.
- 11:29
And it wasn't until we actually like built the whole system that we could see the whole system operate, and we could understand, you know, w-what components of that system do we g-need to go spend time on versus what is just healed by the agentic, uh, sorta nature of the system itself.
- 11:46
And, uh, it was really, I would say, like a mindset shift for many of our teams to not ground themselves in this MVP concept, but to try to just go build the, the whole thing first and then learn from there rather than starting at a smaller component.
- 12:01
So with that, I'll show you just a couple quick demos of some applications that sort of do this work. So the first one is a tax use case. This is like, uh, obviously fake data.
- 12:11
But, you know, you can imagine a tax professional getting a bunch of documents, going through those documents, extracting data, you know, mapping it to a tax calculation engine, et cetera, et cetera, et cetera.
- 12:22
So what, what this product does now is basically take source documents like a W-2 or a 1099 or whatever and, you know, end-to-end does the process of, of generating a tax return.
- 12:36
So we use AI to extract data from the particular documents. We use AI to take that data and understand how to map it to what fields in a tax engine, uh, what those sort of tax laws say about the rules and conditions of those numerical values and whether they should apply in this case or that case or
- 12:56
to this line or to that line, and generate a, a, a tax return end to end. And this is a, a good example of a couple things I just mentioned.
- 13:04
The first is, you know, this is really only possible because we have the tools like a tax engine to be able to give to the model to leverage to, to do these calculations.
- 13:17
Uh, we also have a validation engine that's built into that tax engine that the, the AI system can use to validate the work that it's doing. It can inspect the errors.
- 13:27
It can go look for more information from the documents when it needs it and, and resolve to finish the, the workflow. Um, so I think this is a good example of how we're able to decompose our legacy systems and kinda bring new life to them and, and, and leverage them in, in a unique way.
- 13:45
Um, the second will be, uh, an example of, of legal. This is like a legal research use case, like, uh, where a lawyer might go in and prepare for litigation.
- 13:57
And so, uh, as I mentioned, we have one and a half plus terabytes of proprietary content that we build, uh, our products on. And so this is really like a deep research implementation that is tuned for, uh, legal.
- 14:10
And what we're doing in this particular case, uh, is, uh, having an AI assistant that uses the tools of our litigation research product. So those things would be like searching for documents, fetching documents, uh, comparing citations across cases, validating citations within cases, and is using the components of that application as tools to go out and search
- 14:35
content, retrieve content. It's looking at various different sources of content, whether that be case law or statutes or regulations or legal know-how, you know, articles that we have or other blogs or other content that we've, we've licensed in some way to reason to an appropriate answer to, uh, to a legal research type question.
- 14:57
And what you're seeing here is not necessarily just the, the product, but these are sort of like under the product of like the trajectories that the model would be following along its path of answering this particular type of, of legal question.
- 15:12
And at the end of the flow, uh, the model will-- or along the flow rather, the model will write notes to itself about what it is learning, what it's finding.
- 15:20
And at the end of the flow, will sort of rationalize those notes together into like a, a, a final report that sort of sums up all of the information that was found, uh, throughout the research.
- 15:31
And I think most importantly, what you'll see is, uh, it, it links to hard citations i-in our product. So every sort of blue hyperlink links to like a true case or a str- a true statute, uh, and it flags the, the sort of risk associated with that, with, with, with these flags that you can see.
- 15:50
So, uh, th-these are two examples that I think kinda highlight pretty well, uh, some of those lessons learned that I say around, around decomposing applications, trying to build the whole product at once.
- 16:03
Uh, and these are really things, uh, like I said, that, that we've, we've learned the hard way in, in many cases. So I think just to wrap up, we've got a few minutes and, and we can take a couple questions as well.
- 16:13
But, uh, I, I think beginning with the whole problem in mind is, is, is the right strategy when you're thinking about agentic systems. Uh, I think the way to think about a-agency is, is not as a binary thing, but as a lever that you can dial up or down depending on, uh, the risk or the use case
- 16:32
or the tolerance, uh, of your users for, for certain situations. I think one way to think about agents is to, to bring life back to old systems and, and to sort of break those old systems down into components that can be leveraged uniquely, uh, by an agentic system.
- 16:50
Uh, I th- I think focusing on where humans are in the loop in terms of evaluation, like I said, those, those SMEs that we have i-internally are extremely im-important for us.
- 17:01
And then lastly, I think, you know, the reason we've done what we've done is because we looked at our company, we said, "What are the assets that we have that nobody else has?"
- 17:09
And it's 4,500, you know, domain experts, terabytes of content. And we, we really ask ourselves like, "How can we use those to create the most amount of differentiation in, in our product?"
- 17:20
And so I would, I would, you know, certainly challenge you guys to do the same for yourselves. What are the unique assets that you have, and how can you perhaps best leverage those to, to build uniqueness into whatever applications, uh, it is that you may be doing?
- 17:34
So with that, I think we've got a couple minutes for a couple questions and, and some mics. I think if you guys can bring the mics up to us.
- 17:41
So a great presentation-
- 17:42
You wanna use, use the mic?
- 17:51
A great presentation, Mr. Joel Hron. And, uh, my name is Prabh Bala. I'm a PhD student, and I work for Department of Defense, who sponsor me. Um, so my questions are, um, if I...
- 18:08
You know, it's a, it's a great product. If I have to take the product to my firm, who's Department of Defense or any financial firms, how would you describe the cybersecurity postures, uh, which are mandated by CISA and government recently, such as LLM firewall
- 18:34
or LLM guardrails or, uh, automated, uh, agents for scanning vulnerabilities or any SCM security posture mes- management? How would you define the, uh, cybersecurity posture for the entire architecture?
- 18:52
Yeah. I mean, there, there's certainly a lot of technical documentation on this that I can point you to online. But I would just say that like, you know, w-we're heavily focused on, uh, not just compliance with the standards of like, like FedRAMP and these other things when we work with the government, but also like really trying to
- 19:10
conform to the, the latest standards that are coming out, like the ISO, uh, standard that, uh, recently came out. Several of our products are now, uh, sort of compliant with, with, with that as well.
- 19:21
It's a, it's a pretty quickly evolving space though, so I, I would say w-we're quite adaptable to it.
- 19:29
Anyway, I think I'm getting the hand, but appreciate the time. Thank you very much. And, and we have a booth as well, so, so come, come say hi. [audience applauding] Thanks. [upbeat music]