Setting up the Agent Toolkit for AWS in Kiro (and Codex, Claude Code, and Cursor)

If you've let a coding agent loose on AWS, you've watched it guess. It invents API parameters that don't exist, or hands you an S3 bucket a security review will bounce on sight. The Agent Toolkit for AWS is built to stop that. By the end of this post you'll have it running in whatever editor you use, plus a tour of what's in it and three workflows worth pointing it at. I use Kiro day to day, so I'll walk through that setup first. It also works with Codex, Claude Code, Cursor, and any other agent that speaks MCP, the Model Context Protocol, which is the open standard agents use to connect to outside tools and data. I'll cover those too. What is the Agent Toolkit for AWS? The Agent Toolkit for AWS is a free, AWS-supported set of tools that gives AI coding agents secure access to AWS, current documentation they can read mid-task, and tested procedures for the work they tend to fumble. It plugs into the agent you already use rather than asking you to switch. In practice, that shows up in a few ways, all detailed in the AWS user guide . The agent stops guessing about APIs it never saw. The models behind these agents trained on data that's months or years old, so anything AWS shipped recently is missing or wrong in their heads, and the toolkit hands them current docs and references at request time. For multi-step work like least-privilege IAM or a production serverless stack, it follows a vetted skill instead of reconstructing the steps from half-memory. Every call goes through your own IAM credentials, shows up in CloudWatch, and gets logged to CloudTrail, so you can scope an agent to read-only even when your role can write. And the toolkit costs nothing on its own; you pay only for the AWS resources the agent creates. It's the successor to the MCP servers, skills, and plugins AWS shipped under AWS Labs in 2025. Two things make me reach for it over a raw MCP setup: condition keys that let a policy tell an agent apart from a human, and skills that have been evaluated end