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Don't Build Agents, Build Skills Instead – Barry Zhang & Mahesh Murag, Anthropic

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Don't Build Agents, Build Skills Instead – Barry Zhang & Mahesh Murag, Anthropic

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426 segments

0:13

[music]

0:21

All right, good morning and thank you

0:22

for having us again. Last time we were

0:25

here, we're still figuring out what an

0:26

agent even is. Today, many of us are

0:29

using agents on a daily basis. But we

0:32

still notice gaps. We still have slots,

0:34

right? Agents have intelligence and

0:36

capabilities, but not always expertise

0:38

that we need for real work. I'm Barry.

0:41

This is Mahes. We created agent skills.

0:44

In this talk, we'll show you why we

0:46

stopped building agents and started

0:48

building skills instead.

0:51

A lot of things have changed since our

0:53

last talk. MCP became the standard for

0:55

agent connectivity. Cloud Code, our

0:57

first coding agent, launched to the

0:59

world and our cloud agent SDK now

1:02

provides a production ready agent out of

1:03

the box. We have a more mature ecosystem

1:06

and we're moving towards a new paradigm

1:08

for agents. That paradigm is a tighter

1:11

coupling between the model and a runtime

1:13

environment.

1:15

Put simply, we think code is all we

1:18

need.

1:20

We used to think agents in different

1:22

domains will look very different. Each

1:23

one will need its own tools and

1:25

scaffolding and that means we'll have a

1:27

separate agent for each use case for

1:29

each domain. Well, customization is

1:31

still important for each domain. The

1:34

agent underneath is actually more

1:35

universal than we thought.

1:38

What we realized is that code is not

1:40

just a use case but the universal

1:42

interface to the digital world.

1:44

After we built cloud code, we realized

1:46

that cloud code is actually a general

1:48

purpose agent.

1:50

Think about generating a financial

1:52

report. The model can call the API to

1:54

pull in data and do research. It can

1:56

organize that data in the file system.

1:58

It can analyze it with Python and then

2:00

synthesize the insight in old file

2:02

format all through code. The core

2:04

scaffolding can suddenly become as thin

2:06

as just bash and file system which is

2:09

great and really scalable. But we very

2:11

quickly run into a different problem

2:14

and that problem is domain expertise.

2:16

Who do you want doing your taxes? Is it

2:18

going to be Mahesh, the 300 IQ

2:20

mathematical genius, or is it Barry, an

2:22

experienced tax professional, right? I

2:24

would pick Barry every time. I don't

2:26

want Mahesh to figure out the 2025 tax

2:29

code from first principles. I need

2:30

consistent execution from from a domain

2:33

expert. As agents today are a lot like

2:35

Mahes. They're brilliant, but they lack

2:37

expertise.

2:42

They can do no more slow. They can do

2:44

amazing things when you really put in

2:46

the effort and give proper guidance, but

2:48

they're often missing the important

2:50

context up front. They can't really

2:51

absorb your expertise super well, and

2:53

they don't learn over time.

2:56

That's why we created agent skills.

3:00

Skills are organized collections of

3:02

files that package composable procedural

3:04

knowledge for agents.

3:07

In other words, they're folders. This

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simplicity is deliberate. We want

3:12

something that anyone human or agent can

3:14

create and use as long as they have a

3:16

computer. These also work with what you

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already have. You can version them in

3:20

Git, you can throw them in Google Drive

3:22

and you can zip them up and share with

3:24

your team. We have used files for uh as

3:27

a primitive for decades and we like

3:29

them. So why change now?

3:33

Because of that skills can also include

3:35

a lot of scripts as tools. Traditional

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tools have pretty obvious problems. Some

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tools have poorly written instructions

3:41

and are pretty ambiguous and when the

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model is struggling, it can't really

3:45

make a change to the tool. So, it's just

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kind of stuck with a code start problem

3:49

and they always live in the context

3:50

window. Code solves some of these

3:52

issues. It's self-documenting. It is

3:54

modifiable and can live in the file

3:56

system until they're really needed and

3:58

used. Here's an example of a script

4:02

inside of a skill. We kept seeing Claude

4:04

write the same Python script over and

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over again to apply styling to slides.

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So we just ask cloud to save it inside

4:10

of the skill as a tool for his version

4:12

for his future self. Now we can just run

4:15

the script and that makes everything a

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lot more consistent and a lot more

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efficient.

4:21

At this point skills can contain a lot

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of information and we want to protect

4:25

the context window so that we can fit in

4:27

hundreds of skills and make them truly

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composable. That's why skills are

4:31

progressively disclosed. At runtime,

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only this metadata is shown to the model

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just to indicate that he has the skill.

4:39

When an agent needs to use a skill, it

4:41

can read in the rest of the skill.md,

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which contains the core instruction and

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directory for the rest of the folder.

4:48

Everything else is just organized for

4:51

ease of access. So that's all skills

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are. They're organized folders with

4:56

scripts as tools.

4:59

Since our launch five weeks ago, this

5:02

very simple design has translated into a

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very quickly growing ecosystem of

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thousands of skills. And we've seen this

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be split across a couple of different

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types of skills. There are foundational

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skills, third party skills created by

5:15

partners in the ecosystem, and skills

5:17

built within an enterprise and within

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teams.

5:21

To start, foundational skills are those

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that give agents new general

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capabilities or domain specific

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capabilities that it didn't have before.

5:31

We ourselves with our launch built

5:33

document skills that give Claude the

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ability to create and edit professional

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quality office documents. We're also

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really excited to see people like

5:42

Cadence build scientific research skills

5:45

that give Claude new capabilities like

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EHR data analysis and using common

5:50

Python bioinformatics libraries better

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than it could before.

5:56

We've also seen partners in the

5:57

ecosystem build skills that help Claude

5:59

better with their own software and their

6:01

own products. Browserbase is a pretty

6:04

good example of this. They built a skill

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for their open- source browser

6:08

automation tooling, stage hand. And now

6:10

Claude equipped that this skill and with

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stage hand can now go navigate the web

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and use a browser more effectively to

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get work done.

6:19

And notion launched a bunch of skills

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that help claude better understand your

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notion workspace and do deep research

6:26

over your entire workspace.

6:30

And I think where I've seen the most

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excitement and traction with skills is

6:33

within large enterprises. These are

6:36

company and team specific skills built

6:38

for an organization.

6:41

We've been talking to Fortune 100s that

6:43

are using skills as a way to teach

6:45

agents about their organizational best

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practices and the weird and unique ways

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that they use this bespoke internal

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software.

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We're also talking to really large

6:55

developer productivity teams. These are

6:57

teams serving thousands or even tens of

6:59

thousands of developers in an

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organization that are using skills as a

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way to deploy agents like cloud code and

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teach them about code style best

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practices and other ways that they want

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their developers to work internally.

7:12

So all of these different types of

7:13

skills are created and consumed by

7:15

different people inside of an

7:17

organization or in the world. But what

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they have in common is anyone can create

7:21

them and they give agents the new

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capabilities that they didn't have

7:25

before.

7:28

So, as this ecosystem has grown, we've

7:30

started to observe a couple of

7:32

interesting trends. First, skills are

7:34

starting to get more complex. The most

7:37

basic skill today can still be a

7:39

skill.md markdown file with some prompts

7:42

and some really basic instructions, but

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we're starting to see skills that

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package software, executables, binaries,

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files, code, scripts, assets, and a lot

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more. And a lot of the skills that are

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being built today might take minutes or

7:55

hours to build and put into an agent.

7:58

But we think that increasingly much like

8:00

a lot of the software we use today,

8:02

these skills might take weeks or months

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to build and be maintained.

8:08

We're also seeing that this ecosystem of

8:10

skills is complementing the existing

8:12

ecosystem of MCP servers that was built

8:14

up over the course of this year.

8:16

Developers are using and building skills

8:19

that orchestrate workflows of multiple

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MCP tools stitched together to do more

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complex things with external data and

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connectivity. And in these cases, MCP

8:29

MCP is providing the connection to the

8:31

outside world while skills are providing

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the expertise.

8:37

And finally, and I think most excitingly

8:38

for me personally, is we're seeing

8:40

skills that are being built by people

8:42

that aren't technical. These are people

8:44

in functions like finance, recruiting,

8:46

accounting, legal, and a lot more. Um,

8:50

and I think this is pretty early

8:51

validation of our initial idea that

8:54

skills help people that aren't doing

8:56

coding work extend these general agents

8:59

and they make these agents more

9:00

accessible for the day-to-day of what

9:02

these people are working on.

9:07

So tying this all together, let's talk

9:08

about how these all fit into this

9:10

emerging architecture of general agents.

9:13

First, we think this architecture is

9:15

converging on a couple of things. The

9:17

first is this agent loop that helps

9:20

manage the the model's internal context

9:22

and manages what tokens are going in and

9:24

out. And this is coupled with a runtime

9:26

environment that provides the agent with

9:28

a file system and the ability to read

9:31

and write code.

9:34

This agent, as many of us have done

9:36

throughout this year, can be connected

9:37

to MCP servers. And these are tools and

9:40

data from the outside world that make

9:42

the the agent more relevant and more

9:44

effective.

9:46

And now we can give the same agent a

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library of hundreds or thousands of

9:51

skills that it can decide to pull into

9:53

context only at runtime when it's

9:55

deciding to work on a particular task.

9:58

Today, giving an agent a new capability

10:01

in a new domain might just involve

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equipping it with the right set of MCP

10:05

servers and the right library of skills.

10:09

And this emerging pattern of an agent

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with an MCP server and a set of skills

10:14

is something that's already helping us

10:16

at Enthropic deploy Claude to new

10:17

verticals. Just after we launched skills

10:20

5 weeks ago, we immediately launched new

10:22

offerings in financial services and life

10:25

sciences. And each of these came with a

10:27

set of MCP servers and a set of skills

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that immediately make Claude more

10:31

effective for professionals in each of

10:33

these domains.

10:37

We're also starting to think about some

10:38

of the other open questions and areas

10:40

that we want to focus on for how skills

10:42

evolve in the future as they start to

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become more complex. We really want to

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support developers, enterprises, and

10:49

other skill builders by starting to

10:52

treat skills like we treat software.

10:54

This means exploring testing and

10:56

evaluation, better tooling to make sure

10:59

that these agents are loading and

11:01

triggering skills at the right time and

11:03

for the right task, and tooling to help

11:06

measure the output quality of an agent

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equipped with the skill to make sure

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that's on par with what the agent is

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supposed to be doing.

11:14

We'd also like to focus on versioning.

11:16

as a skill evolves and the resulting

11:18

agent behavior uh evolves, we want this

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to be uh clearly tracked and to have a

11:23

clear lineage over time.

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And finally, we'd also like to explore

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skills that can explicitly depend on and

11:30

refer to either other skills, MCP

11:33

servers, and dependencies and packages

11:35

within the agents environment. We think

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that this is going to make agents a lot

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more predictable in different runtime

11:41

environments. and the composability of

11:43

multiple skills together will help

11:45

agents like Claude elicit even more

11:47

complex and relevant behavior from these

11:49

agents.

11:51

Overall, these set of things should

11:53

hopefully make skills easier to build

11:55

and easier to integrate into agent

11:56

products, even those besides claude.

12:02

Finally, a huge part of the value of

12:04

skills we think is going to come from

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sharing and distribution. Barry and I

12:09

think a lot about the future of

12:11

companies that are deploying these

12:12

agents at scale. And the vision that

12:15

excites us most is one of a collecting

12:18

and collective and evolving knowledge

12:20

base of capabilities that's curated by

12:23

people and agents inside of an

12:25

organization. We think skills are a big

12:28

step towards this vision. They provide

12:30

the procedural knowledge for your agents

12:32

to do useful things. And as you interact

12:35

with an agent and give it feedback and

12:38

more institutional knowledge, it starts

12:40

to get better and all of the agents

12:42

inside your team and your org get better

12:44

as well. And when someone joins your

12:47

team and starts using Claude for the

12:48

first time, it already knows what your

12:50

team cares about. It knows about your

12:52

day-to-day and it knows about how to be

12:54

most effective for the work that you're

12:55

doing.

12:56

And as this grows and this ecosystem

12:58

starts to develop even more, this was

13:00

going to this compounding value is going

13:02

to extend outside of just your organ

13:04

into the broader community. So just like

13:06

when someone else across the world

13:08

builds an MCP server that makes your

13:09

agent more useful, a skill built by

13:11

someone else in the community will help

13:13

make your own agents more capable,

13:15

reliable, and useful as well.

13:20

This vision of a evolving knowledge base

13:22

gets even more powerful when claw starts

13:24

to create these skills. We design skills

13:27

specifically as a concrete steps towards

13:29

uh continuous learning.

13:31

When you first start using cloud, this

13:33

standardized format gives a very

13:35

important guarantee. Anything that cloud

13:37

writes down can be used efficiently by a

13:39

future version of itself. This makes the

13:42

learning actually transferable.

13:44

As you build up the context skills makes

13:46

the concept of memory more tangible.

13:49

They don't capture everything. They

13:51

don't capture every type of information.

13:52

Just procedural knowledge that cloud can

13:54

use on specific tasks.

13:57

When you have worked with cloud for

13:59

quite a while, the flexibility of skills

14:01

matters even more. Cloud can acquire new

14:04

capabilities instantly, evolve them as

14:06

needed, and then drop the ones that

14:08

become obsolete. This is what we have

14:10

always known. The power of in in context

14:12

learning makes this a lot more cost-

14:14

effective for information that change on

14:16

daily basis.

14:18

Our goal is that claude on day 30 of

14:20

working with you is going to be a lot

14:22

better on cloud on day one. CL can

14:24

already create skills for you today

14:26

using our skill creator skill and we're

14:28

going to continue pushing in that

14:29

direction.

14:33

We're going to conclude by comparing the

14:35

agent stack to what we have already seen

14:37

computing.

14:38

In a rough analogy, models are like

14:41

processors. Both require massive

14:44

investment and contain immense

14:46

potential, but only so useful by

14:48

themselves.

14:50

Then we start building operating system.

14:52

The OS made processors far more valuable

14:54

by orchestrating the processes,

14:56

resources, and data around the

14:58

processor. In AI, we believe that agent

15:00

runtime is starting to play this role.

15:02

We're all trying to build the cleanest,

15:04

most efficient, and most scalable uh

15:06

abstractions to get the right tokens in

15:09

and out of the model.

15:11

But once we have a platform, the real

15:13

value comes from applications. A few

15:16

companies build uh processors and

15:18

operating systems, but millions of

15:20

developers like us have built software

15:23

that encoded domain expertise and our

15:25

unique points of view. We hope that

15:27

skills can help us open up this layer

15:30

for everyone. This is where we get

15:32

creative and solve concrete problem for

15:34

ourselves, for each other, and for the

15:35

world just by putting stuff in the

15:37

folder. So skills are just the starting

15:39

point.

15:42

To close out, we think we're now

15:44

converging on this general architecture

15:46

for general agents. We've created skills

15:48

as a new paradigm for shipping and

15:51

sharing new capabilities. So we think

15:53

it's time to stop rebuilding agents and

15:55

start building skills instead. And if

15:57

you're excited about this, come work

15:59

with us and start building some skills

16:01

today. Thank you.

16:05

[music]

16:17

>> [music]

Interactive Summary

The presentation introduces 'agent skills' as a new paradigm for enhancing AI agents. Instead of building specialized agents for every domain, the speakers argue that agents should be universal, while 'skills'—which are organized folders containing scripts and procedural knowledge—provide the necessary domain expertise. These skills allow agents to remain lightweight, composable, and capable of learning over time, mimicking how traditional software development encodes domain expertise. The speakers envision an evolving, community-driven knowledge base where both humans and agents can create, share, and improve these skills, ultimately making agents more effective and tailored to specific organizational needs.

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