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The AI Agent block

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The AI Agent block is an AI assistant that can automate tasks in Postman Flows. There are two AI Agent blocks v1, and v2. The AI Agent v1 block responds to natural language prompts by analyzing data, generating content, making decisions, and calling other flows. The AI Agent v2 block does the same, but instead of calling other flows, it invokes tools exposed by MCP Servers.

The AI Agent blocks use one of several AI models to interpret prompts and act on available context. You can pass data to the block as variables in the Context section, and each variable’s label helps the block understand the variable’s purpose. The AI Agent v1 block can also use other flows as tools to complete its tasks. The AI Agent v2 block can use MCP Servers to build agents that can complete autonomous tasks.

For example, you could give the AI Agent v1 block a list of API endpoints as a variable named endpoints_list. Then, you could select a flow from the Tools section that sends a GET request to a provided endpoint. When you prompt the AI Agent v1 block to “Get the content headers for each endpoint in endpoints_list,” it will automatically run the tool for each one and output the results. Or you could give the AI Agent v2 block a Slack channel ID and add a Slack MCP Server to create an agent that sends updates to the Slack channel with the ID you provided.

Input

Context - Variables you can reference in your prompt using plain text. The variable’s name is called a label here because the AI Agent block interprets context about the variable’s value from the its label. For example, an endpoints label provides more context than a label like variable-1. Click Add icon Add data blocks to add more variables. You can add variables to the Context section using any of the following data blocks:

Outputs

Result - Sends the result of the AI Agent block’s task.

Setup

Model - Select the AI model from the dropdown list that best suits your task. Different models consume different amounts of credits. See Manage your team’s Postman Flows credit usage for details about how the AI Agent block consumes credits.

Prompt - The system prompt for the AI agent. A system prompt is static and persists for the duration of the task. Enter a prompt in natural language that describes what you want your agent to do. You can reference variables in the prompt by including the variables’ labels as plain text. If you added tools to the block, the AI Agent block will automatically use them if needed to act on the prompt.

Tools - Tools are flows your AI Agent v1 block can run automatically. The AI Agent v1 block tries to generate any input data it needs from its own knowledge or from variables you’ve provided. To use a flow as a tool, the flow must have at least one snapshot.

To add a tool, do the following:

  1. Click the AI Agent v1 block.

  2. Click Add a tool.

  3. Select a tool from the dropdown list.

To select a different snapshot of a tool, do the following:

  1. Hover over the tool.

  2. Click Versions icon.

  3. Select a snapshot from the dropdown list.

When a tool uses inputs, the AI Agent v1 block automatically populates those inputs with AI-generated data. You can also assign static values to the inputs with a configuration.

Postman Flows doesn’t pass static configuration data to the LLM to preserve the security of any secrets.

To select a configuration for a tool, do the following:

  1. Hover over a tool.

  2. Click Setting icon Edit Tool.

  3. Next to the input, click Magic icon AI-generated.

  4. Select a configuration from the dropdown list or click Open web icon Add configuration to create a new one.

MCP Servers - MCP Servers expose specific functionalities that the AI Agent v2 block can use to create agents to automate tasks.

To add an MCP Server, do the following:

  1. Click the AI Agent v2 block.

  2. Click Add server.

  3. Enter a name for your MCP server.

  4. Enter the MCP Server URL.

  5. (Optional) Enter a bearer token if your MCP Server requires one. When you enter a bearer token, Postman Flows saves it as a secret value in a new configuration. The next time you add an MCP Server, you can choose to reuse that secret bearer token or create a new one.

  6. Click Add to add the MCP Server.

Additional Settings - Appears when you click the block, and enables you to select an AI model or enforce an output schema that you can parse later in the flow.

To enforce an output schema, do the following:

  1. Click the AI Agent block, then click Setting icon Additional Settings.

  2. Click JSON icon Enforce output schema > JSON icon Schema.

  3. Click Generate from example and paste valid JSON data into the text box, then click Generate schema. Alternatively, click Define custom schema to manually enter a JSON schema.