Brad Menezes, CEO of enterprise vibe coding startup Superblocks, believes the next crop of billion-dollar startup ideas are hiding in almost plain sight: the system prompts used by existing unicorn AI startups.
System prompts are the lengthy prompts — over 5,000-6,000 words — that AI startups use to instruct the foundational models from companies like OpenAI or Anthropic on how to generate their application-level AI products. They are, in Menezes view, like a master class in prompt engineering.
“Every single company has a completely different system prompt for the same [foundational] model,” he told TechCrunch. “They’re trying to get the model to do exactly what’s required for a specific domain, specific tasks.”
System prompts aren’t exactly hidden. Customers can ask many AI tools to share theirs. But they aren’t always publicly available.
So as part of his own startup’s new product announcement of an enterprise coding AI agent named Clark, Superblocks offered to share a file of 19 system prompts from some of the most popular AI coding products like Windsurf, Manus, Cursor, Lovable and Bolt.
Menezes’s tweet went viral, viewed by almost 2 million including big names in the Valley like Sam Blond, formerly of Founders Fund and Brex, and Aaron Levie, a Superblocks investor. Superblocks announced last week that it raised a $23 million Series A, bringing its total to $60 million for its vibe coding tools geared to non-developers at enterprises.
So we asked Menezes to walk us through how to study other’s system prompts to glean insights.
“I’d say the biggest learning for us building Clark and reading through the system prompts is that the system prompt itself is maybe 20% of the secret sauce,” Menezes explained. This prompt gives the LLM the baseline of what to do.
The other 80% is “prompt enrichment” he said, which is the infrastructure a startup builds around the calls to the LLM. That part includes instructions it attaches to a user’s prompt, and actions taken when returning the response, such as checking for accuracy.
Roles, context and tools
He said there are three parts of system prompts to study: role prompting, contextual prompting, and tool use.
The first thing to notice is that, while system prompts are written in natural language, they are …