Add a tool to an agent (Microsoft Copilot)

You can add tools to your agent from the Build tab. Tools let your agent perform actions, connect to external services, and retrieve real-time data during conversations.

Note

The harness used to build this agent uses usage-based billing. Using, building, testing, and evaluating agents might consume Copilot Credits. Learn more in Overview of usage-based billing.

Prerequisites

  • An agent created with the Microsoft Copilot harness. Learn more in Create an agent.

Add an existing tool from the Build tab

  1. Sign in to Copilot Studio and open your agent.

  2. In the agent navigation bar, select the Build tab.

  3. In the components panel, select the Tools button.

  4. In the Add a tool dialog, browse or search for the tool you want to add. Use the Featured, Model Context Protocol (MCP), Connectors, or Workflows tabs to filter by tool type. When you enter a search term, the Featured tab is replaced by an All tab that shows matching results across all tool types.

  5. Select the tool to view its details, including a description and the actions it provides.

    Note

    If your organization blocked a tool due to data policies, you can't select it.

  6. Select Add to add the tool to your agent.

Tools blocked by your organization's policies

Your organization can use governance policies to restrict which tools and connectors are available in Copilot Studio.

When a data policy blocks a tool, the tool appears unavailable in the Add a tool panel and you can't select it. Hover over the cross icon next to the unavailable tool to see why the tool isn't available. In some environments, an info icon appears instead. Select it to open a Blocked by policy explanation.

Screenshot showing a tool blocked by a data policy in the Add a tool panel.

The message explains that your organization's data policy blocks the tool, so the tool can't be used, even by an agent, and publishing or running an agent that uses it can fail. If you need access to a blocked tool, contact your administrator.

Learn more in Configure data policies for agents.

Configure a tool after adding it

After adding a tool, you might need to:

  • Authenticate: Some tools require you to sign in or provide credentials before you can use them. Follow the authentication prompts when they appear. When a tool signs in with each user's own account, users set up their connection the first time the agent needs it. Learn more in Set up your connections when an agent asks.
  • Select actions: For connectors that provide multiple actions, you can select which specific actions to make available to your agent.
  • Review the description: Make sure the tool's description accurately reflects what it does. The agent's orchestration runtime uses the description to determine when to invoke the tool.

Add a new custom tool

If the tool you need isn't listed in the Add a tool dialog, you can add a custom tool. Agents powered by the Microsoft Copilot harness support the following custom tools:

To start, select the Add button in the Add a tool dialog, then select Model Context Protocol (MCP) or Workflow.

  • MCP tools from an existing Model Context Protocol (MCP) server. Use MCP tools to connect to custom services, databases, or APIs that expose capabilities as tools through the MCP standard.
  • Workflows that you create in Copilot Studio's flow designer. Use workflows to define multi-step processes that your agent can run on demand.

Files your agent creates

Some tools produce files as their output - for example, a generated report, spreadsheet, or image. Each file is capped at 10 MB, and files that exceed the cap aren't returned to the user. Learn more in Files the agent creates (Microsoft Copilot) (preview).

Tips for effective tool descriptions

Tip

The tool name and description are important for accurate tool invocation. The enhanced orchestration runtime uses them to decide when to invoke a tool, so:

  • Use clear, specific names that describe the tool (for example, "Create support ticket" rather than "Ticket tool").
  • Write descriptions that explain when to use the tool and what it returns.
  • Avoid vague or overlapping descriptions between tools.
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