Nicolas Bustamante
Founder of Fintool; builder of AI agents for professional investors in financial services.
Last updated: 2026-04-12
Overview
Nicolas Bustamante (@nicbstme) has spent two-plus years building Fintool, an AI agent platform for professional investors. He writes publicly about the hard-won architectural lessons from operating in a domain where wrong numbers cost real money.
He is an early adopter of filesystem-first agentic design, having moved Fintool away from RAG/vector pipelines to agentic search after discussing the approach with Thariq from Anthropic’s Claude Code team. He wrote “The RAG Obituary” documenting that decision, which generated significant debate when published.
Key Ideas
- The experience is the product: the model is a commodity; the moat is data, skills, UX, and domain trust
- Skills as first-class citizens: markdown-based skills are the product, not prompt engineering — non-engineers (analysts, portfolio managers) can write and iterate on skills without code deployment
- Design for obsolescence: build skills knowing future models will need less scaffolding; use markdown over code because it’s easier to delete
- Fear as a feature: in high-stakes domains, paranoid attention to correctness becomes a product differentiator
Connections
- agent-sandbox — Fintool’s per-user sandbox architecture
- context-normalization — Fintool’s financial data normalization pipeline
- s3-first-architecture — Fintool’s storage pattern
- agent-evaluation — Fintool’s eval-driven development practices
- claude-code-skills — Fintool’s skills system mirrors the Anthropic Agent Skills spec
- thin-harness-fat-skills — validated by Fintool’s production experience
Sources
- Lessons from Building AI Agents for Financial Services — added 2026-04-12