Does the agent harness matter when using Clay with the same model?
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Clay AI agent benchmark: same model, different harness
With Clay, the same Kimi K3 model averaged 83.0 out of 100 across five GTM data tasks in Factory and 70.3 in OpenCode, and most of that gap came from two OpenCode runs that hit the 60-minute limit. On the runs both harnesses finished, they were about 2 points apart, and OpenCode was usually faster and cheaper in model cost. So yes, the harness matters, mainly through whether a run finishes.
By The Prompting Company · Snapshot November 5, 2026
The question
An AI coding agent is a model plus a harness: the program that runs the model, calls tools and decides when to stop. Our Clay benchmark ran Kimi K3 in two harnesses, OpenCode and Factory, which lets us hold the model and Clay constant and see what the harness changes. We call them OpenCode Kimi and Factory Kimi below.
Task by task
Primary score out of 100, averaged over three runs with a timeout counted as 0. Clay credits are measured as the change in the Clay workspace credit balance, and minutes from run start to grading.
| Task | OpenCode Kimi | Factory Kimi | OpenCode credits | Factory credits | OpenCode minutes | Factory minutes |
|---|---|---|---|---|---|---|
| Work emails | 93.0 | 93.0 | 352 | 378 | 5.1 · 3.7 · 8.7 | 8.7 · 4.8 · 15.3 |
| Company data | 58.0 | 85.9 | 731 | 445 | 31.0 · 9.5 · 60.6 | 48.9 · 7.9 · 7.8 |
| CMO | 48.3 | 74.7 | 916 | 1,007 | 60.6 · 17.2 · 27.6 | 23.2 · 40.3 · 17.9 |
| Job changes | 93.7 | 94.7 | 1,405 | 1,486 | 8.6 · 13.5 · 10.3 | 21.0 · 15.4 · 23.3 |
| Target list | 58.7 | 66.7 | 156 | 225 | 9.9 · 6.4 · 3.7 | 10.2 · 9.0 · 5.3 |
| All five | 70.3 | 83.0 | 3,560 | 3,541 | 276.4 total | 259.0 total |
Factory Kimi passed 11 of its 15 runs and OpenCode Kimi passed 9. Their Clay credit totals were within 20 of each other.
Where the two harnesses agreed
Work emails. Both sent contacts to Clay's Work Email routine and found the same 93 of 100 in every run.
Job changes. Both ran Clay's Enrich Person and Find Contact Details on all 100 LinkedIn profiles in every run (Factory Kimi's first run sent 119 items, the others 101), caught 42 of the 45 people who had moved, and scored 93 to 96. OpenCode Kimi finished in 8.6 to 13.5 minutes; Factory Kimi took 15.4 to 23.3.
On these two tasks the harness changed the time, not the answer.
Where the scores differed
Run length. Two OpenCode Kimi runs reached the 60-minute limit and count as 0: its third company data run and its first CMO run. On the runs it finished, OpenCode Kimi averaged 87.0 on company data and 72.5 on CMOs, against Factory Kimi's 85.9 and 74.7. Its overall average would be 81.0 against Factory's 83.0.
CMO method. Factory Kimi's first CMO run used the low-cost method the CMO post describes, free people search first and then one Work Email per chosen person, and found 80 for 312 credits. That method keeps the cost under 3 credits per company and the run short.
Target list. OpenCode Kimi scored 44, 66 and 66, and Factory Kimi 74, 62 and 64. The method that scored highest on this task works in either harness: check that each company is listed in its own name and headquartered in the US before adding it.
Model cost
| OpenCode Kimi | Factory Kimi | |
|---|---|---|
| Reported model cost | $13.88 over 13 runs | $19.29 over 15 runs |
| Average per reported run | $1.07 | $1.29 |
The test platform did not report model cost for OpenCode Kimi's two timed-out runs.
What this means for your Clay setup
The harness controls how a run is carried out, and in this benchmark the difference showed up mainly in run length. When both harnesses finished, the same model with the same Clay method produced close to the same score. For any harness, the safest step is to name the Clay method in the prompt, so the agent goes straight to the low-cost path. For all seven agents, see "Which AI coding agent gets the most out of Clay?".
How we tested
Seven agents, including OpenCode with Kimi K3 and Factory with Kimi K3, ran each of five tasks three times, one agent at a time, in a fresh sandbox with the same Clay key, the same 19 saved Clay routines and a 60-minute limit. A timeout counts as 0; platform failures were rerun. Pass lines: 70 for emails; 90 for domain and HQ and 70 for headcount and funding; 70 for CMO name and title and 60 for email; 80 for job changes; 70 qualifying companies and a full list of 100 for the target list. Tasks and graders: github.com/promptingcompany/clay-bench.
Try it yourself
The Clay Agent Plugin ships Clay's skills to your agent up front, including the habits that keep credit use down; setup is one prompt (about 15 minutes), and there is no additional cost to use it. Use the Clay Agent Plugin or a Clay API key with the Clay Public API docs in either harness, and include the method in your prompt: Work Email directly for emails, people search before any paid lookup for CMOs, one enrichment per profile for job changes.
Common questions
Does the agent harness matter when using Clay with the same model? Yes: Kimi K3 averaged 83.0 in Factory and 70.3 in OpenCode, mostly because two OpenCode runs hit the 60-minute limit.
Which Kimi K3 harness was faster? OpenCode Kimi: its finished runs averaged less time than Factory Kimi's on all five tasks, for example 8.6 to 13.5 minutes on job changes against 15.4 to 23.3.
Did the harness change Clay credit spend? Barely in total: 3,560 credits for OpenCode Kimi and 3,541 for Factory Kimi for one average run of all five tasks.
Which harness passed more runs? Factory Kimi, 11 of 15 against 9 for OpenCode Kimi.