Mastra

Mastra Framework Guide

Build AI applications with Mastra. This skill teaches you how to find current documentation and build agents and workflows.

Critical: Do not trust internal knowledge

Everything you know about Mastra is likely outdated or wrong. Never rely on memory. Always verify against current documentation.

Your training data contains obsolete APIs, deprecated patterns, and incorrect usage. Mastra evolves rapidly - APIs change between versions, constructor signatures shift, and patterns get refactored.

Prerequisites

Before writing any Mastra code, check if packages are installed:

ls node_modules/@mastra/

• If packages exist: Use embedded docs first (most reliable)
• If no packages: Install first or use remote docs

Resources

References

Scripts

• scripts/provider-registry.mjs: Look up current providers and models available in the model router. Always run this before using a model to verify provider keys and model names.

Priority order for writing code

Never write code without checking current docs first.

1. Embedded docs first (if packages installed)

   Look up current docs in node_modules for a package. This matches the exact installed version and is the most reliable source of truth. See references/embedded-docs.md.

2. Source code second (if packages installed)

   If embedded docs don't cover the question, inspect the installed source and type definitions. This is the source of truth when docs are missing or unclear. See references/embedded-docs.md.

3. Remote docs third (if packages not installed)

   Use the latest published docs when packages are not installed or when exploring new features. Remote docs may be ahead of the user's installed version. See references/remote-docs.md.

Core concepts

Use references/core-concepts.md when choosing between agents, workflows, tools, memory, and storage.

• Agent: Use for open-ended tasks that make decisions and use tools.
• Workflow: Use for defined multi-step processes.

Mastra Studio

Studio is the interactive UI for building, testing, and managing agents, workflows, and tools. Use Studio when advising a human to inspect or debug visually.

Inside a Mastra project, run:

npm run dev

Then open http://localhost:4111 in a browser to show Mastra Studio to your human user.

Mastra API CLI

Use mastra api to inspect or call resources on local dev servers, Mastra platform deployments, or remote Mastra endpoints. It is useful for agent-readable state, execution, traces, logs, scores, threads, and workflow operations. See references/mastra-api.md for usage patterns.

Critical requirements

TypeScript config

Mastra requires ES2022 modules. CommonJS will fail. See references/create-mastra.md for setup and references/common-errors.md for troubleshooting.

Model format

Always use "provider/model-name" when defining models using Mastra's model router.

When the user asks to use a model or provider, always run scripts/provider-registry.mjs first to verify the provider key and model name are valid. Do not guess model names from memory as they change frequently. See references/model-selection.md.

When you see errors

Type errors often mean your knowledge is outdated.

Common signs of outdated knowledge:

• Property X does not exist on type Y
• Cannot find module
• Type mismatch errors
• Constructor parameter errors

What to do:

1. Check references/common-errors.md
2. Verify current API in embedded docs
3. Don't assume the error is a user mistake - it might be your outdated knowledge

Development workflow

Always verify before writing code:

1. Check whether Mastra packages are installed
2. Look up current API
   • If installed: Use embedded docs references/embedded-docs.md
   • If not: Use remote docs references/remote-docs.md
3. Write code based on current docs
4. Test with the project scripts or Studio when available