Mercury Senior Software Engineer at Mercury working on Command, an LLM-powered financial assistant. Responsible for designing and shipping new Command skills and agentic workflows, maintaining the LLM layer, and ensuring product quality.
Responsibilities
Ship new capabilities users love:
Design and ship new Command skills, the domain-specific instruction sets that teach the model how to handle workflows like sending money, managing invoices, and understanding cash flow
Design and build agentic workflows in Command, defining the architecture for how multi-step agent interactions should work as we extend what the product can do on a customer's behalf
Work with backend teams to define tool schemas for new capabilities, shaping the data contracts between Mercury's business logic and the model
Own new capabilities end to end, from the system prompt to the frontend component that renders the response
Own the LLM layer:
Maintain and evolve Command's prompt architecture: the system prompt, skill loading system, session context, and the policy and compliance layers underneath
Tune model behavior: reasoning effort, prompt caching strategy, fallback chains, and the streaming patterns that make the product feel fast
Stay current with how models are evolving and bring that knowledge back to how Command is built
Build quality in:
Write and expand Command's eval harness, adding cases that cover new capabilities and scoring rubrics that detect regressions before users do
Partner with product and compliance teams to define what "working correctly" means for each new capability, then build the tests that prove it
Qualification
Required
7 or more years of software engineering experience
Deep technical expertise building and scaling LLM-powered applications in production
