Senior Agent Designer

Topline Pro; Boston; On-site; PHP 7,658,000 - 11,487,000; Full time

Benefits offered by this job

YC-backed

Job summary

Topline Pro is looking for a lead designer to become the first dedicated to Sidekick Labs, shaping how Sidekick thinks, behaves, and presents itself across apps and partner surfaces. You will define prompts, rubrics, and system rules, and ensure the agent’s work is trustable and transparent.

You will report to the VP of Design and collaborate with the Head of App Experience, Sidekick Labs engineers, and the product manager to audit, pattern, and scale agent design across ten products.

Qualifications

• 6+ years of product design experience with a strong shipped portfolio.
• 2+ years designing LLM-powered products live with real users (agents, assistants, copilots).
• Experience writing prompts and system instructions that shipped.
• Ability to read traces, identify where an agent went wrong, and explain why.
• Think in systems; design patterns that scale across multiple agents.
• Clear, plain copy is central to product in agent products.
• Experience researching with non-tech users and adapting to their workflows.
• Prototype in code (HTML, CSS, JS, or React Native) with AI tooling.
• Stay close to model capabilities and design for future limits and opportunities.
• Strong craft; UI that is polished and trusted.
• Experience delivering complex products end to end in undefined spaces.
• Thrives in small, fast teams with evolving problems.

Responsibilities

• Define the target Sidekick behavior, tone, and decision points across products.
• Audit current Sidekick usage and set patterns for cross-platform consistency.
• Design prompts and system rules that govern agent actions and error handling.
• Show work and explain reasoning to pros through transparent outputs.
• Design waiting experiences for complex requests to feel fast and controlled.
• Create discoverability patterns that teach pros about Sidekick capabilities.

Skills

Product design

LLM-powered products

Prompt engineering

Trace analysis

Systems thinking

Clear writing

Prototype coding

React Native

Claude Code

Tools

Claude Code

Job description

Role

You will be the first designer dedicated to Sidekick Labs. You will design how Sidekick (our AI agent) thinks, behaves, and acts, not just how it looks. That means the conversation, the moments where Sidekick hands over a real thing (a quote, an invoice, a post), how it shows its work, how it recovers when it gets something wrong, and how a Pro finds out what it can do. You'll write the prompts and the rubrics that define "good." Then you'll check the traces to see if we hit it.

You’ll report to the VP of Design and work closely with our Head of App Experience, Sidekick Labs engineers and product manager.

What you'll work on

• One Sidekick, everywhere - Sidekick shows up across the app, the web dashboard, and partner surfaces. Today Sidekick is only available on our mobile app and is not available for all our products. You'll lead the audit and set the patterns to fix that.

• From chat to artifact - A pro says "okay, make it a quote." Sidekick keeps writing text. You'll design the handoff from conversation to real, editable work.

• Show your work - Pros trust what they can see. You'll design how Sidekick explains what it did and why, without burying a busy pro in detail.

• The wait - Complex requests take time. You'll design the waiting experience so Sidekick feels fast and in control, even when it's thinking.

• Discoverability - Our bet is that pros adopt features by talking to Sidekick, not by hunting through menus. You'll figure out how Sidekick teaches a pro what it can do, at the right moment.

• Agent behavior - Define tone, clarifying questions vs. just acting, error recovery, confirmation before anything goes out to a customer. You'll own these as design decisions and write them into prompts and system rules.

• Evals - You'll define what a good response looks like, write the rubrics, label real conversations, and work with engineering to turn that into automated checks.

• The cookbook - You'll turn what we learn into reusable agent design patterns other pods can pick up and use. Think design system, but for agent behavior.

• New conventions - Most of the patterns for agents don't exist yet. You'll invent new ones that feel obvious to a pro the first time they see them.

• Where Sidekick goes next - You'll help shape the Sidekick Labs roadmap with the PM and engineers. You'll bring a point of view on what we should build, not just how it should look.

What you bring

• 6+ years of product design, with a strong portfolio of shipped work.

• 2+ years designing LLM-powered products that are live with real users. Agents, assistants, or copilots. Not just concepts.

• You've written prompts and system instructions that shipped. You know how a small wording change moves behavior.

• You're comfortable in the weeds. You can read a trace, spot where an agent went wrong, and say why.

• You think in systems. You can design a pattern once and make it work across ten agents.

• You write clearly and plainly. In an agent product, the copy is the product.

• You've done research with people who aren't tech-first, and you respect how they work.

• You prototype in code. HTML, CSS, and JavaScript, or React Native, with help from AI tools like Claude Code. You use prototypes to test behavior against the real model, not just screens.

• You stay close to the models. You know what the latest ones can and can't do, and you design for where they're going, not where they were six months ago.

• Your craft is strong. Your UI is polished, clear, and builds trust.

• You've owned complex products end to end in messy, undefined spaces, and shipped anyway.

• You're happy in a small, fast team where the problem isn't fully defined yet.

About Sidekick Labs

Sidekick Labs is our AI agent team that is focused on making our agents trustworthy for the pros who use them, and for the teams who build them.

We have three jobs:

1. Build a platform other teams can build on. Any pod at Topline Pro should be able to ship an agent without us holding their hand.

2. Build a conversational experience Pros trust. Every agent should feel like one Sidekick. Pros stay in control while Sidekick does the work.

3. Build agents we're confident in. Every agent completes real tasks correctly, and we can prove it.

About Topline Pro

We're building an AI-powered Shopify for service businesses. We help service pros (e.g., roofers, landscapers, painters, cleaners) acquire direct business, fast. Up and running within minutes using Gen AI, our digital storefront products help pros get discovered, trusted, and booked repeatedly.
We're YC-backed and well-funded, with several years of runway, and we've experienced rapid growth over the past year. We're in a phenomenal position to scale, with the financial foundation, product-market fit, and momentum to go big. You'll be joining at an inflection point, where the groundwork is laid, and the path to massive impact is clear.
We believe "great candidates" do not come about simply from a check mark next to past experience. We believe in hiring people, not just skills. Topline Pro is committed to building an inclusive workplace and assembling a team from diverse backgrounds. We ensure that individuals with disabilities receive reasonable accommodation throughout the application and interview process. We strongly encourage applications from underrepresented candidates and those from nontraditional backgrounds.