Who Is Noah Shinn, the Founder of Instinct?

Noah Shinn is the 23-year-old founder and chief executive officer (CEO) of Spear Street Technology, the company behind the artificial intelligence (AI) personal assistant Instinct.

At Layer3Labs, we build AI agents for small-business workflows, so we read a founder's research for what it says about how the product will behave.

Before founding Instinct, Shinn was a research scientist at Sierra, where he was the first author of the Reflexion paper and co-authored τ-bench.

Noah Shinn in Brief

Shinn is a former Sierra research scientist who now runs Instinct as CEO. In August 2026, Instinct raised a $250 million Series B at a $2.5 billion valuation, as reported by TechCrunch.

Before starting Instinct, Shinn worked on foundational research for autonomous software agents. He was first author of Reflexion, a method for language agents that learn from their own failed attempts, and KuCoin reports he was one of Sierra's earliest employees. At Sierra, he also co-authored τ-bench to measure agent reliability.

Vellum, which develops competing software, says Instinct is based in San Francisco. PYMNTS reports that Instinct is in an invitation-only beta. Users interact with Instinct through text messages and voice calls without installing dedicated applications.

Education and Early Research

Before Sierra, Noah Shinn worked on machine learning and programming language research at Northeastern University and the Massachusetts Institute of Technology (MIT), per his Sierra author page. According to KuCoin, citing The Wall Street Journal and BlockBeats, Shinn dropped out of Northeastern University in 2023.

Reflexion and Verbal Reinforcement

Noah Shinn served as the first author of Reflexion, a research paper establishing that autonomous software agents can learn through linguistic self-reflection instead of parameter updates. The paper, titled "Reflexion: Language Agents with Verbal Reinforcement Learning," was first submitted to arXiv in March 2023. The co-authors on the paper include Federico Cassano, Edward Berman, Ashwin Gopinath, Karthik Narasimhan, and Shunyu Yao.

Reflexion agents verbally reflect on task feedback signals, then maintain their own reflective text in an episodic memory buffer to induce better decision-making in subsequent trials. Traditional reinforcement learning requires updating underlying model weights when an error occurs. Reflexion avoids retraining weights entirely by storing critique notes in text form for future attempts.

The authors updated the paper across four versions in 2023. The paper was presented at NeurIPS 2023. The paper reports these coding results.

• The paper recorded a 91% pass@1 accuracy on the HumanEval coding benchmark.
• The result surpassed the previous state-of-the-art GPT-4 baseline of 80% reported in the study.

Sierra and the Development of τ-bench

Noah Shinn worked as a research scientist at Sierra, where he co-developed the τ-bench evaluation framework for conversational software agents. SiliconANGLE describes Sierra as an AI startup led by former OpenAI board chair Bret Taylor.

During his tenure at Sierra, Shinn co-authored the benchmark paper titled "τ-bench: A Benchmark for Tool-Agent-User Interaction in Real-World Domains," published on arXiv in June 2024. The paper was co-authored by Shunyu Yao, Noah Shinn, Pedram Razavi, and Karthik Narasimhan. The benchmark evaluates how effectively autonomous agents navigate multi-step workflows while interacting with simulated users and external application programming interfaces (APIs).

On March 18, 2025, Shinn published a post on Sierra's blog about how τ-bench is shaping agent development and evaluation. The benchmark checks whether the database ends in the right state after an agent talks with a simulated customer, repeated across several tries (how τ-bench is scored).

Founding of Instinct and Spear Street Technology

Noah Shinn founded Instinct, a personal assistant you reach by text or phone call. The corporate entity behind Instinct is Spear Street Technology, Inc., doing business as Instinct. SiliconANGLE reported that Instinct entered the consumer AI scene in February 2026 by making Instinct available through an invite-only private beta program.

Reports vary regarding the founding timeline of Instinct. PYMNTS reported that Instinct was founded in 2025. TechCrunch reported in August 2026 that Instinct was founded one year earlier. Corporate filings in California show Spear Street Technology was registered in April 2026, according to TechFundingNews and Vellum citing Forbes.

Instinct is marketed as a personal assistant that organizes personal tasks and daily schedules. Instinct connects to a user's email, messaging tools, calendar, and device signals. Users communicate with Instinct by text message or voice calls. In September 2026, Instinct introduced Instinct Concierge in early access to handle voice calls for appointments and reservations, as reported by TechCrunch.

TechCrunch reported in August 2026 that Instinct's own bot named Luca Borletti, also formerly of Sierra, as involved with Instinct, and that this had not been confirmed. Borletti's personal site lists his role as founding engineer at Instinct starting in November 2025, after working as a software engineer at Sierra from June to November 2025. It does not describe him as a co-founder.

Funding History and Capital Rounds

TechCrunch reported that Instinct had raised $350 million in total by August 2026. On August 26, 2026, Shinn announced the Series B round on X. TechCrunch and TechFundingNews reported that the $250 million round was co-led by Index Ventures and Benchmark. PYMNTS reported the valuation at $2.25 billion, while TechCrunch and TechFundingNews reported $2.5 billion.

Accounts of earlier financing rounds vary. SiliconANGLE, citing The Wall Street Journal, reported a prior $100 million round from Conviction Partners and Greenoaks. TechFundingNews reported an early backing that valued Instinct at $50 million. TechFundingNews also reported that Kleiner Perkins led a $75 million Series A at a $500 million valuation in early August.

In September 2026, PYMNTS, citing The Information, reported that Spear Street Technology was in talks to raise $1 billion at a $10 billion valuation. The report stated that the invite-only user base of Instinct had passed 100,000. Funding figures change as rounds close, so check TechCrunch's August 2026 report before you cite one.

• TechCrunch put total capital raised at $350 million as of late August 2026.
• The Series B round secured $250 million, co-led by Index Ventures and Benchmark.
• Reports of pre-Series B funding conflict: $100 million per SiliconANGLE citing The Wall Street Journal, or a $75 million Series A per TechFundingNews.
• September 2026 reports indicated ongoing discussions for a $1 billion round at a $10 billion valuation.

Connections Between Agent Research and Commercial Tools

Noah Shinn's research deals with two problems that acting assistants face with real users, recovering from failed attempts and following rules reliably. In academic papers, Shinn investigated how software agents recover from failed actions and conform to strict operational boundaries. Those exact challenges appear when an assistant manages personal inboxes, schedules rides, and completes online transactions.

However, Instinct does not publish whether Instinct uses Reflexion or τ-bench mechanisms internally. Vellum says Instinct runs a proprietary model only on Spear Street Technology's own servers. Instinct's privacy policy says Instinct shares data with third-party AI model providers, and no official statement names the model. Readers evaluating Instinct should not assume Instinct runs identical algorithms to Shinn's academic papers.

Operational challenges have emerged during early user testing of Instinct. Users posted complaints about email indexing and deletion on X, which TechCrunch reported, and the team at Instinct later added a data-deletion tool in settings. Under the terms of service of Instinct, users appoint Instinct as their legal agent to enter into binding agreements on their behalf. If you are weighing Instinct for work email, Instinct's terms and data practices set out what it can do in your accounts.

Name Disambiguation in Search Results

Searches for Noah Shinn also return student athletes who share the name. Additionally, Instinct from Spear Street Technology is a different company from Instinct Science.

To see what Instinct connects to and how access works, start with how Instinct works.