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Build Notes

Lessons from building AI agent systems for real businesses. No hype, no affiliate links. Just what we learned, what we'd pick again, and what we'd avoid.

Note 1: Choosing an LLM for Business Agent Tasks

ModelsCostUpdated March 2025

Not every task needs the most powerful model. Most business agent tasks — drafting replies, summarizing data, categorizing messages — work well with mid-tier models. Save the expensive models for complex reasoning.

Decision matrix

Task typeGood enoughWhen to upgrade
Auto-replies & acknowledgmentsGPT-4o-mini, Claude Haiku, Gemini FlashRarely — these are templated
Summarization & reportingGPT-4o-mini, Claude SonnetLong documents or multi-source synthesis
Client communication draftsClaude Sonnet, GPT-4oHigh-stakes or nuanced tone required
Complex analysis & planningClaude Opus, GPT-4oDefault to best available
Code generation & debuggingClaude Sonnet, GPT-4oMulti-file refactors, security-critical code
Rule of thumb: Start with the cheapest model that produces acceptable output. Upgrade per-task, not globally. A single agent can route different tasks to different models. Most businesses can run 80% of agent tasks on mini/haiku-tier models at under $20/month.

Deeper dive: How to Choose an LLM →

Note 2: Agent Platforms — What Actually Matters

PlatformsArchitecture

The platform you build your agent on matters less than you think. What matters: can it connect to your tools, can a non-developer maintain it, and will it still work when you're not watching?

What to evaluate

Our take: For service businesses under 20 people, start with a platform that handles the orchestration (OpenClaw, n8n, Make) and connect it to the models via API. Avoid platforms that lock you into a specific model provider. You will want to switch models — the landscape changes every 3 months.

Deeper dive: How to Choose an Agent Platform →

Note 3: Security Basics for AI Agent Systems

SecurityNon-Negotiable

AI agents touch your client data, your communication channels, and your business tools. Security isn't optional — even for a 3-person shop.

Minimum security checklist

The bar is low — clear it. Most agent security failures aren't sophisticated attacks. They're credentials left in a Notion doc, an agent with admin access it doesn't need, or nobody checking the logs. Fix those three things first.

Related: MSA Security Resources →

Note 4: Integration Patterns That Actually Work

ArchitectureIntegrations

Every AI agent project involves connecting systems. Here's what we've seen work reliably vs. what causes ongoing pain.

Reliable patterns

Patterns that cause pain

Keep it boring. The best agent integrations are the ones that are easy to explain, easy to test, and easy to fix at 11pm when something breaks. Clever architectures are fun to design and miserable to maintain.

Note 5: What We Got Wrong (And Fixed)

LessonsHonesty

Building in public means sharing mistakes too. Here's what bit us.

Next step

Use these notes to choose one tooling decision this week and document the result after 14 days.

Apply with a playbook →