# What is a Budget

> Understand how budgets control your AI agent's access to tools, spending limits, and credentials.

Content type: documentation
Source URL: https://www.agentpmt.com/docs/core-concepts/what-is-a-budget
Markdown URL: https://www.agentpmt.com/docs/core-concepts/what-is-a-budget?format=agent-md
Category: Core Concepts

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# What is a Budget

A **budget** is the control layer between you and your AI agent. It defines what tools the agent can use, how much it can spend, and what credentials it has access to.

Every tool call your agent makes goes through a budget. No budget, no access.

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## What a Budget Controls

- **Tool Access**: Only tools added to the budget are visible to your agent.
  - **Spending Caps**: Set limits per-call, hourly, daily, weekly, or monthly.
  - **Credentials**: Bind API keys and OAuth tokens so tools can authenticate on your behalf.

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## One Agent, Multiple Budgets

You can create multiple budgets for different purposes:

| Budget | Use Case | Cap |
|--------|----------|-----|
| Research Agent | Web search, data retrieval | 500 credits/day |
| Content Writer | Writing tools, image generation | 200 credits/day |
| Shopping Agent | Product search, ordering | 50 credits per call |

Each budget has its own **budget key**. When you connect an agent, the budget key determines which budget it operates under.

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## Budget Keys

Every budget generates a unique **budget key**. Combined with your **API key**, these two keys authenticate your agent:

- **API Key** -- Identifies you (same across all budgets)
- **Budget Key** -- Identifies which budget the agent uses

Your agent sends both keys with every request. AgentPMT checks the budget to verify the tool is allowed and the spending cap hasn't been exceeded.

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## Agent Address

Each budget can have an **agent address** -- a blockchain wallet address assigned to that budget. This is used for on-chain payments via the x402 protocol. You can generate or recycle an agent address from the budget settings.

> INFO
>
> Agent addresses are optional. If you're only using credits (not on-chain payments), you don't need one.

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## Next Steps

- [Set Up Your First Budget](/docs/monitoring/setting-up-your-first-budget) - Step-by-step budget creation
  - [Setting Spending Caps](/docs/payments-and-billing/setting-spending-caps) - Learn about cap types and strategies