How to register Mastra agents dynamically at runtime from a database?

Question

In Mastra, every agent must be declared in code before the app starts. For multi-tenant use cases, I need users or an admin UI to create agents at runtime with their own prompt, tools, and configuration, stored in a database. Is there a way to register agents on the fly without redeploying?

Originally asked on GitHub: https://github.com/mastra-ai/mastra/issues/4050

AgentArmorHQ team · Accepted Answer

As of the issue close (July 2025), dynamic on-the-fly agent registration is not a built-in Mastra feature. A maintainer closed the request saying it is possible to implement in your application logic, and a contributor provided a runtime workaround.

Create a new `Mastra` instance per user/request, loading its config from your own storage, and avoid using `mastra build/dev` for this flow:

```ts
const getMastra = (userId) => {
  const config = await getConfig(userId)
  return new Mastra(config)
}

app.get('/agents', (c) => {
  const userId = getUserid()
  const agents = (await getMastra()).getAgents()
  return json({agents})
})
```

The thread does not confirm this was actually tested; it is a suggested approach. One caveat raised in the discussion is that `RuntimeContext` only makes certain agent parts (like instructions and tools) dynamic, not memory. A maintainer also said they are open to a PR to make more agent arguments dynamic, and a contributor referenced an implementation example at https://github.com/deco-cx/chat/blob/main/packages/ai/src/agent.ts.

If your deployment relies on `mastra build/dev`, this factory-based approach will need extra work to fit your pipeline.

AgentArmorHQ team · Answer

**What @wardpeet tried on GitHub** (Outcome unclear)

Suggested a workaround: create a new Mastra instance per user/request with config loaded from storage, avoiding mastra build/dev. Provided code for getMastra(userId) and getAgents(). Outcome was not confirmed in the thread.

Source: https://github.com/mastra-ai/mastra/issues/4050#issuecomment-3008572013

AgentArmorHQ team · Answer

**What @pedrofrxncx tried on GitHub** (Outcome unclear)

Pointed to a reference implementation at github.com/deco-cx/chat, saying it is possible but 'you need to implement it'. No details on what the linked code does were given.

Source: https://github.com/mastra-ai/mastra/issues/4050#issuecomment-3016910680

How to register Mastra agents dynamically at runtime from a database?

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How to register Mastra agents dynamically at runtime from a database?

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