Which tools do Claude, Codex and Cursor choose? We measured 17k runs to find out

[OP] screm | 6 hours ago

Hey!

Disclaimer: I am a Co-Founder of Armature (YC P26) which sells growth services to dev tools. This study is part of our broader work on how to influence coding agents choices and get products picked.

To understand how agents pick tools we measured close to 17k sessions on an environment where agents run exactly like in the real world, on various repositories, talking to different personas (vibe-coder, junior or senior engineers) in different sizes of companies.

All the results are now public and we'd love to know what findings surprise you the most, here are a few we found interesting: - Claude Code rarely searches the web while Codex almost always does it and Cursor sits in the middle. - Coding agents disagree more frequently than they agree. - Some players (LangChain, Supabase, Netlify, Paypal, Adyen) are almost always mentioned in their categories but never chosen. - Modifying repository context can change the pick entirely.

If you feel like digging, all the traces are there and we probably missed interesting learnings so let us know what you find!

vivifkjo | 5 hours ago

Is there a way to force the usage of a tool for certain tasks? Example: alawys use cli "foobar" to retrieve weather starus.

By tool I mean mcp server, cli, etc.

[OP] screm | 5 hours ago

Not sure I got your question right but if you are wondering for your own coding agent then I guess the answer would be a skill? Here what I meant by "how to influence coding agents choices and get products picked" is from a vendor PoV, making sure any developer x codebase in the world asking for a tool in your category gets your tool recommended and implemented by the coding agent.

watusername | 5 hours ago

Obviously you can ask the agent to use a specific tool, but the point of this article is about what they choose when the human on the other end has no opinion/taste/clue.

[OP] screm | 5 hours ago

Exactly!

josephg | 5 hours ago

The data was cool. Then I tried to tap on one of the other tabs. “This content is easier to read while full screen!” - Ok I’m game. “Hey this is what makes armature special!” - I don’t care, I’m here to look at data, not onboard onto some random platform. It took ages to find the tiny “skip tour” button, hiding in black on black text. Then it gave me another popup, which I dismissed without reading. Then the full screen modal was visible but it was horizontally misaligned - the left edge was cut off and the right of my phone screen was all white. I closed the tab with great prejudice. (Safari on iOS if you wanna try reproducing it)

I’m sure you - or Claude - built something you’re proud of. But I left your website frustrated.

[OP] screm | 5 hours ago

Hey, thanks for the feedback, the leaderboards aren't displaying well on mobile indeed, we are currently shipping a fix that should help with that. Thanks anyway!

kouteiheika | 5 hours ago

FWIW I had the same reaction to the popups. Immediately closed the tab.

[OP] screm | 5 hours ago

Yep makes sense I’m relaxing them

[OP] screm | 4 hours ago

It should be better now, including in mobile, thanks both for the feedback!

hbarka | 3 hours ago

> Claude Code rarely searches the web while Codex almost always does

I’m trying to understand why they are opposite. I think it is true, I find myself giving a secondary prompt to Claude to “research this” and only then will it fetch. Codex is bang on fetching already.

edoceo | 3 hours ago

Gemini CLI (at least mine) does web research all the time. I've noticed it hitting my own pages (I have to ask very specific things). I don't have any global or project rules to encourage that behavior.

arcanemachiner | 18 minutes ago

Must be system prompts and tool instructions guiding the agents differently.

ai_critic | 3 hours ago

Hi. I appreciate that you need to make rent, but if your business is basically "we do growth hacking and SEO tricks on models and get them to use products that aren't actually best for the job", you are scum.

You are perpetuating shitty practices that have hurt developers for years now. Part of the reason people use AI is because of how useless search is due to the previous generation doing the same kind of thing you propose.

Please do something else with your life.

jdw64 | 5 hours ago

Looking at this, maybe in the future, the tools that AI prefers will become the mainstream. Even now, the tools that AI gives the highest priority to are the ones people already choose. There might be a concentration effect toward the tools that AI selects

[OP] screm | 5 hours ago

Definitely! But about concentration I'm not so sure, there are ways to counter this effect so in the end it will be a fight like SEO is today. What is certain though is that getting recommended by coding agents will be a top prio for all dev tools.

ex-aws-dude | 5 hours ago

In the future: "I went ahead and built the database you requested using today's tool sponsor: Firebase"

[OP] screm | 5 hours ago

Yeah sounds kind of like the equivalent of SEA for AI agents (AEA?) except that it’s sneakier since agents can act without you noticing.. anyway this is in the hands of the labs

edoceo | 3 hours ago

Is SEA Search Engine Advertising? So AEA is Agent Engine Advertising?

pupppet | 4 hours ago

Ugh...this is totally going to happen.

Onavo | 3 hours ago

Not going to name names but it's already happening with the frontier labs as a revenue source.

folkrav | 2 hours ago

I feel like you legitimately cannot say it for legal reasons, but I wish we would just name these freaking things.

paulhebert | 2 hours ago

Didn’t OpenAI claim they’re going to make a billion dollars off ads in a year or something?

BikiniPrince | 2 hours ago

The framework recommendations are always funny, but the worst is database layout. I made the mistake of assuming it has some reasonable sense.

drivingmenuts | 5 hours ago

I smell a money-making opportunity.

[OP] screm | 5 hours ago

Haha there is a lot at stake for sure

hbarka | 3 hours ago

Redshift for databases ain’t even here. This is suspect.

ai_critic | 3 hours ago

Can we not encourage the same strip-mining and ad and SEO bullshit that previously ruined the last decade+ of the Internet?

A large portion of the utility of AI is the barren ad-driven growth-hacked hellscape search has become. Don't encourage the next generation of these businesses, I beg of everyone.

edoceo | 3 hours ago

Large amounts of capital want this to happen? Outside of boycott, what else can be done.

What can man do against such reckless ~hate~ money?

folkrav | 2 hours ago

It is probably already happening, and will get worse. OpenAI was boasting about their advertising revenue mere days ago.

If we felt like we couldn't trust AI because of slop, soon we won't be able to trust it because it'll push whatever pays them to do it.

DrewADesign | an hour ago

And while these sponsorship shenanigans are the tech business’s bread and butter, sponsored answer manipulation seems fundamentally more insidious. Even in a larger-scale measurement like this one, there’s no way to tell if any of that is sponsored, legitimately good recommendations, or the technical flavor of the goblins problem.

ttul | 3 hours ago

I built this for my own company. Armature is on to something. You start by analyzing the choices agents would make for various use cases and then glean what, if anything, you might do to start tilting the agents in the direction of your own product and away from the competitor.

Selling to agents is similar to selling to humans. You dump money into marketing to make sure agents find your solution around every corner for every use case you’re well suited to.

tiffanyh | an hour ago

Doesn’t this ignore that the future of ads will probably just be some type of affiliate revenue going back to the agent for any product they help recommend.

appplication | 31 minutes ago

Maybe but that future isn’t now and there’s real money to be made today with the above strategy.

hexapus | 50 minutes ago

Well that's a horrifying thought. Thanks, I hate it.

akurilin | 2 hours ago

Really liked that "Go Full Screen" as a modal flow, surprisingly intuitive.

luciana1u | 2 hours ago

the 17k runs are the real headline here, not which tool won. we finally have someone measuring the thing everyone else is just vibing about.

mpalmer | an hour ago

Using LLMs to write comments is against guidelines, even if you make the text lowercase.

thedreammachine | 2 hours ago

I've been tracking the same for a few months. All open source and available here: https://preseason.ai/

negativefactori | an hour ago

nice!

IgorPartola | 2 hours ago

For some reason Claude Code keeps using awk, sed, and even Python to do basic file editing. Anyone know why that changed with the 5 series?

rcfox | an hour ago

I've noticed that too. Maybe the normal Write tool has to output the entire file and this is an attempt to reduce token usage?

pjm331 | an hour ago

The Edit tool has been notoriously tricky to get right - it seems they have maybe branched out but I think morphllm started specifically with the pitch that they trained a small model to be good at editing files - most of their testimonials are about that

But I think it’s mostly a solved problem in frontier models and the bash tool usage is more likely an attempt to be more token efficient - I’ve noticed it used for making mechanical bulk edits that would be numerous “edit” tool uses otherwise

ryeguy | an hour ago

What does this question have to do with the linked article?

nijave | an hour ago

Actually, yes. Probably this https://github.com/anthropics/claude-code/issues/88041#issue...

elzbardico | an hour ago

I remember when the SEO nightmare started, it looked like an innocent intelectual investigation exercise like this.

nijave | an hour ago

Azure database??? In house bot protection??? In house search???

Some of these are absolutely wild. Surprised Strands didn't even get mentioned for agent frameworks.

natnatenathan | 13 minutes ago

I keep telling people that we are living in the golden age of AI - like the first year or two of google. It is all down hill as these companies push for profit and lock-in.