How to integrate Postman MCP with Pydantic AI

GET STARTED FOR FREE
Framework Integration Gradient
Postman Logo
Pydantic AI Logo
divider

Introduction

This guide walks you through connecting Postman to Pydantic AI using the Composio tool router. By the end, you'll have a working Postman agent that can run the 'get users' request in postman, list all collections in my postman workspace, create a new environment variable in postman through natural language commands.

This guide will help you understand how to give your Pydantic AI agent real control over a Postman account through Composio's Postman MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

TL;DR

Here's what you'll learn:
  • How to set up your Composio API key and User ID
  • How to create a Composio Tool Router session for Postman
  • How to attach an MCP Server to a Pydantic AI agent
  • How to stream responses and maintain chat history
  • How to build a simple REPL-style chat interface to test your Postman workflows

What is Pydantic AI?

Pydantic AI is a Python framework for building AI agents with strong typing and validation. It leverages Pydantic's data validation capabilities to create robust, type-safe AI applications.

Key features include:

  • Type Safety: Built on Pydantic for automatic data validation
  • MCP Support: Native support for Model Context Protocol servers
  • Streaming: Built-in support for streaming responses
  • Async First: Designed for async/await patterns

What is the Postman MCP server, and what's possible with it?

The Postman MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Postman account. It provides structured and secure access so your agent can perform Postman operations on your behalf.

Supported Tools & Triggers

Tools
Create a CollectionTool to create a new Postman collection in a specific workspace or the default workspace.
Create a Collection CommentTool to create a comment on an API's collection.
Create Collection from SchemaTool to create a collection from a schema and link it to an API with specified relations.
Create a FolderTool to create a folder in a Postman collection.
Create a Folder CommentTool to create a comment on a folder.
Create a ForkTool to create a fork from an existing collection into a workspace.
Create Environment ForkTool to create a fork from an existing environment into a workspace.
Create a Mock ServerTool to create a new mock server in a Postman collection.
Create a MonitorTool to create a new monitor in a specific workspace to run a collection on a schedule.
Create an APITool to create a new API in Postman.
Create an APITool to create a new API in a Postman workspace.
Create an EnvironmentTool to create a new environment in a Postman workspace.
Create a Pull RequestTool to create a pull request for a forked collection into its parent collection.
Create Request in CollectionTool to create a new request in a Postman collection.
Create a Request CommentTool to create a comment on a request.
Create a ResponseTool to create a request response in a Postman collection.
Create a Response CommentTool to create a comment on a response.
Create API SchemaTool to create a schema for an API in Postman.
Create Mock Server ResponseTool to create a server response on a Postman mock server.
Create a SpecTool to create an API specification in Postman's Spec Hub.
Create Spec FileTool to create a new file in an API specification.
Create a WebhookTool to create a webhook that triggers a collection with a custom payload.
Create a WorkspaceTool to create a new workspace in Postman.
Create CollectionTool to create a new Postman collection with specified name and configuration.
Create EnvironmentTool to create a new Postman environment with specified name and variables.
Create Mock ServerTool to create a new mock server for a Postman collection.
Create MonitorTool to create a new monitor to run a collection on a schedule.
Create or Update a Schema FileTool to create or update an API schema file in Postman.
Create API Version RelationsTool to create new relations for an API version.
Create WebhookTool to create a new webhook for a Postman collection.
Delete a CollectionTool to permanently delete a collection from Postman.
Delete a collection's commentTool to delete a comment from an API's collection.
Delete a FolderTool to delete a folder in a Postman collection.
Delete a Folder's CommentTool to delete a comment from a folder.
Delete an APITool to delete an API from Postman.
Delete an API's CommentTool to delete a comment from an API.
Delete an environmentTool to delete an environment permanently in Postman.
Delete a Request's CommentTool to delete a comment from a request.
Delete a ResponseTool to delete a response in a Postman collection.
Delete a Response's CommentTool to delete a comment from a response.
Delete a Schema FileTool to delete a file in an API schema.
Delete Mock Server ResponseTool to delete a mock server's server response.
Delete a SpecTool to delete an API specification from Postman.
Delete Spec FileTool to delete a file from an API specification.
Delete a WorkspaceTool to delete a Postman workspace permanently.
Delete MonitorTool to delete a monitor by its ID.
Duplicate a CollectionTool to create a duplicate of a collection in another workspace.
Fork CollectionTool to create a fork of a collection in a specified workspace.
Generate Collection from SpecTool to generate a Postman collection from an OpenAPI 2.
Generate Spec from CollectionTool to generate an API specification from a Postman collection.
Get Billing Account DetailsTool to retrieve Postman billing account details for the authenticated team.
Get Collection CommentsTool to retrieve all comments left by users in an API's collection.
Get Collection's ForksTool to get all forks of a specific collection.
Get Collection Pull RequestsTool to get information about a collection's pull requests including source and destination IDs, status, and URLs.
Get Collection RolesTool to get information about all roles in a collection.
Get Folder InformationTool to retrieve information about a folder in a Postman collection.
Get Folder CommentsTool to retrieve all comments left by users in a folder.
Get All API ReleasesTool to get all releases for a specific API version in Postman.
Get All APIsTool to get all APIs accessible to the authenticated user with optional workspace filtering.
Get All APIs in WorkspaceTool to get all APIs in a specific Postman workspace.
Get All CollectionsTool to get all collections accessible to the authenticated user with optional workspace filtering.
Get All CollectionsTool to get all collections accessible to the authenticated user.
Get All EnvironmentsTool to get all environments accessible to the authenticated user with optional workspace filtering.
Get All Forked CollectionsTool to retrieve all forked collections for the authenticated user.
Get All GroupsTool to get all user groups in a Postman team.
Get All Linked RelationsTool to retrieve all linked relations for a specific API version in Postman.
Get All Mock ServersTool to get all active mock servers accessible to the authenticated user.
Get All MonitorsTool to get all monitors accessible to the authenticated user with optional workspace filtering.
Get All Workspace RolesTool to get information about all roles in a workspace based on the team's plan.
Get All API SpecificationsTool to get all API specifications in a workspace.
Get All Team UsersTool to get information about all users on the Postman team.
Get All Test RelationsTool to retrieve all test relations for a specific API version.
Get All API VersionsTool to get all published versions of a specific API in Postman.
Get All WorkspacesTool to get all workspaces accessible to the authenticated user with optional type filtering.
Get Monitor InformationTool to retrieve information about a specific monitor in Postman.
Get API InformationTool to retrieve information about a specific API in Postman.
Get API CommentsTool to retrieve all comments left by users in an API.
Get API VersionTool to get information about a specific API version in Postman.
Get an EnvironmentTool to retrieve detailed information about a specific environment in Postman.
Get Environment ForksTool to retrieve all forked environments for a specific environment.
Get Request InformationTool to retrieve information about a specific request in a Postman collection.
Get Request CommentsTool to retrieve all comments left by users in a request.
Get Response InformationTool to retrieve information about a saved response in a Postman collection.
Get Response CommentsTool to retrieve all comments left by users in a response.
Get API SchemaTool to retrieve information about an API schema from Postman.
Get API SpecificationTool to retrieve information about an API specification in Postman.
Get Spec File ContentsTool to get the contents of an API specification's file.
Get Spec DefinitionTool to get the complete contents of an API specification's definition.
Get Specification FilesTool to retrieve all files in an API specification from Postman.
Get Spec's Generated CollectionsTool to retrieve all collections generated from an API specification in Postman.
Get Async Collection Update StatusTool to get the status of an asynchronous collection update task.
Get Team UserTool to get information about a user on the Postman team.
Get Authenticated UserTool to get information about the authenticated user.
Get Workspace DetailsTool to get detailed information about a specific workspace by its ID.
Get Workspace Activity FeedTool to get a workspace's activity feed showing who added or removed collections, environments, or elements, and users joining or leaving.
Get Workspace RolesTool to get the roles of users, user groups, and partners in a workspace.
Get Collection Access KeysTool to retrieve all personal and team collection access keys for the authenticated user.
Get Contract Test RelationsTool to retrieve contract test relations for a specific API version.
Get documentation relationsTool to get documentation relations for a specific API version.
Get Duplication Task StatusTool to get the status of a collection duplication task.
Get Environment RelationsTool to get environment relations for a specific API version.
Get Generated SpecificationTool to retrieve the API specification generated for a Postman collection.
Get Workspace Global VariablesTool to get a workspace's global variables.
Get Integration Test RelationsTool to get integration test relations for a specific API version.
Get Resource TypesTool to get all resource types supported by Postman's SCIM API.
Get Schema File ContentsTool to get the contents of an API schema file at a specified path.
Get Schema FilesTool to retrieve files in an API schema from Postman.
Get Service Provider ConfigurationTool to get Postman's SCIM API service provider configuration information.
Get Source Collection StatusTool to check whether there is a change between a forked collection and its parent (source) collection.
Get Test Suite RelationsTool to get test suite relations for a specific API version.
Get Unclassified RelationsTool to get unclassified relations for an API version in Postman.
Import OpenAPI DefinitionTool to import an OpenAPI definition into Postman as a new collection.
Import OpenAPI SpecificationTool to import an OpenAPI specification into Postman as a new collection.
List Account InvoicesTool to get all invoices for a Postman billing account filtered by status.
Merge a ForkTool to merge a forked collection back into its parent collection.
Merge a forked environmentTool to merge a forked environment back into its parent environment.
Publish a Mock ServerTool to publish a mock server in Postman.
Pull Source Changes into ForkTool to pull changes from a parent (source) collection into a forked collection.
Replace an Environment's DataTool to completely replace an environment's data with new variables and values.
Replace Collection Data AsynchronouslyTool to replace the entire contents of a collection asynchronously.
Resolve a Comment ThreadTool to resolve a comment thread and any associated replies.
Review a Pull RequestTool to update the review status of a pull request by approving, declining, or unapproving it.
Run a MonitorTool to trigger an immediate run of a monitor and retrieve its execution results.
Sync Collection with API SchemaTool to sync a collection attached to an API with the API schema.
Sync Collection with SpecificationTool to sync a collection generated from an API specification.
Sync Spec with CollectionTool to sync an API specification with a linked collection.
Transfer FoldersTool to copy or move folders into a collection or folder.
Transform Collection to OpenAPITool to transform an existing Postman Collection into a stringified OpenAPI 3.
Update a FolderTool to update a folder in a Postman collection.
Update a Folder's CommentTool to update a comment on a folder.
Update a Mock ServerTool to update an existing mock server.
Update a MonitorTool to update an existing monitor in Postman.
Update an APITool to update an existing API in Postman.
Update an API's CommentTool to update a comment on an API.
Update an EnvironmentTool to update specific environment properties using JSON Patch operations (RFC 6902).
Update a Pull RequestTool to update an open pull request in Postman.
Update Request in CollectionTool to update a request in a Postman collection.
Update a Request's CommentTool to update a comment on a request.
Update a ResponseTool to update a response in a Postman collection.
Update a Response's CommentTool to update a comment on a response.
Update a Server ResponseTool to update a mock server's server response.
Update Spec FileTool to update an API specification file's content.
Update Spec PropertiesTool to update an API specification's properties such as its name.
Update a WorkspaceTool to update an existing workspace in Postman.
Update Workspace Global VariablesTool to update and replace a workspace's global variables.
Update Collection PropertiesTool to update specific collection properties like name, description, authentication, variables, or events.

What is the Composio tool router, and how does it fit here?

What is Tool Router?

Composio's Tool Router helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Tool Router

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Tool Router works

The Tool Router follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Prerequisites

Before starting, make sure you have:
  • Python 3.9 or higher
  • A Composio account with an active API key
  • Basic familiarity with Python and async programming

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.

Install dependencies

bash
pip install composio pydantic-ai python-dotenv

Install the required libraries.

What's happening:

  • composio connects your agent to external SaaS tools like Postman
  • pydantic-ai lets you create structured AI agents with tool support
  • python-dotenv loads your environment variables securely from a .env file

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your agent to Composio's API
  • USER_ID associates your session with your account for secure tool access
  • OPENAI_API_KEY to access OpenAI LLMs

Import dependencies

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()
What's happening:
  • We load environment variables and import required modules
  • Composio manages connections to Postman
  • MCPServerStreamableHTTP connects to the Postman MCP server endpoint
  • Agent from Pydantic AI lets you define and run the AI assistant

Create a Tool Router Session

python
async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for Postman
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["postman"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")
What's happening:
  • We're creating a Tool Router session that gives your agent access to Postman tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned session.mcp.url is the MCP server URL that your agent will use

Initialize the Pydantic AI Agent

python
# Attach the MCP server to a Pydantic AI Agent
postman_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
agent = Agent(
    "openai:gpt-5",
    toolsets=[postman_mcp],
    instructions=(
        "You are a Postman assistant. Use Postman tools to help users "
        "with their requests. Ask clarifying questions when needed."
    ),
)
What's happening:
  • The MCP client connects to the Postman endpoint
  • The agent uses GPT-5 to interpret user commands and perform Postman operations
  • The instructions field defines the agent's role and behavior

Build the chat interface

python
# Simple REPL with message history
history = []
print("Chat started! Type 'exit' or 'quit' to end.\n")
print("Try asking the agent to help you with Postman.\n")

while True:
    user_input = input("You: ").strip()
    if user_input.lower() in {"exit", "quit", "bye"}:
        print("\nGoodbye!")
        break
    if not user_input:
        continue

    print("\nAgent is thinking...\n", flush=True)

    async with agent.run_stream(user_input, message_history=history) as stream_result:
        collected_text = ""
        async for chunk in stream_result.stream_output():
            text_piece = None
            if isinstance(chunk, str):
                text_piece = chunk
            elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                text_piece = chunk.delta
            elif hasattr(chunk, "text"):
                text_piece = chunk.text
            if text_piece:
                collected_text += text_piece
        result = stream_result

    print(f"Agent: {collected_text}\n")
    history = result.all_messages()
What's happening:
  • The agent reads input from the terminal and streams its response
  • Postman API calls happen automatically under the hood
  • The model keeps conversation history to maintain context across turns

Run the application

python
if __name__ == "__main__":
    asyncio.run(main())
What's happening:
  • The asyncio loop launches the agent and keeps it running until you exit

Complete Code

Here's the complete code to get you started with Postman and Pydantic AI:

python
import asyncio
import os
from dotenv import load_dotenv
from composio import Composio
from pydantic_ai import Agent
from pydantic_ai.mcp import MCPServerStreamableHTTP

load_dotenv()

async def main():
    api_key = os.getenv("COMPOSIO_API_KEY")
    user_id = os.getenv("USER_ID")
    if not api_key or not user_id:
        raise RuntimeError("Set COMPOSIO_API_KEY and USER_ID in your environment")

    # Create a Composio Tool Router session for Postman
    composio = Composio(api_key=api_key)
    session = composio.create(
        user_id=user_id,
        toolkits=["postman"],
    )
    url = session.mcp.url
    if not url:
        raise ValueError("Composio session did not return an MCP URL")

    # Attach the MCP server to a Pydantic AI Agent
    postman_mcp = MCPServerStreamableHTTP(url, headers={"x-api-key": COMPOSIO_API_KEY})
    agent = Agent(
        "openai:gpt-5",
        toolsets=[postman_mcp],
        instructions=(
            "You are a Postman assistant. Use Postman tools to help users "
            "with their requests. Ask clarifying questions when needed."
        ),
    )

    # Simple REPL with message history
    history = []
    print("Chat started! Type 'exit' or 'quit' to end.\n")
    print("Try asking the agent to help you with Postman.\n")

    while True:
        user_input = input("You: ").strip()
        if user_input.lower() in {"exit", "quit", "bye"}:
            print("\nGoodbye!")
            break
        if not user_input:
            continue

        print("\nAgent is thinking...\n", flush=True)

        async with agent.run_stream(user_input, message_history=history) as stream_result:
            collected_text = ""
            async for chunk in stream_result.stream_output():
                text_piece = None
                if isinstance(chunk, str):
                    text_piece = chunk
                elif hasattr(chunk, "delta") and isinstance(chunk.delta, str):
                    text_piece = chunk.delta
                elif hasattr(chunk, "text"):
                    text_piece = chunk.text
                if text_piece:
                    collected_text += text_piece
            result = stream_result

        print(f"Agent: {collected_text}\n")
        history = result.all_messages()

if __name__ == "__main__":
    asyncio.run(main())

Conclusion

You've built a Pydantic AI agent that can interact with Postman through Composio's Tool Router. With this setup, your agent can perform real Postman actions through natural language. You can extend this further by:
  • Adding other toolkits like Gmail, HubSpot, or Salesforce
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows (for example, Gmail + Postman for workflow automation)
This architecture makes your AI agent "agent-native", able to securely use APIs in a unified, composable way without custom integrations.

How to build Postman MCP Agent with another framework

OpenAI Agents SDK

OpenAI Agents SDK

Use Postman MCP with OpenAI Agents SDK

Claude Agent SDK

Claude Agent SDK

Use Postman MCP with Claude Agent SDK

Google ADK

Google ADK

Use Postman MCP with Google ADK

LangChain

LangChain

Use Postman MCP with LangChain

Vercel AI SDK

Vercel AI SDK

Use Postman MCP with Vercel AI SDK

Mastra AI

Mastra AI

Use Postman MCP with Mastra AI

LlamaIndex

LlamaIndex

Use Postman MCP with LlamaIndex

CrewAI

CrewAI

Use Postman MCP with CrewAI

Claude Code

Claude Code

Use Postman MCP with Claude Code

Codex

Codex

Use Postman MCP with Codex

FAQ

What are the differences in Tool Router MCP and Postman MCP?

With a standalone Postman MCP server, the agents and LLMs can only access a fixed set of Postman tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Postman and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with Pydantic AI?

Yes, you can. Pydantic AI fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Postman tools.

Can I manage the permissions and scopes for Postman while using Tool Router?

Yes, absolutely. You can configure which Postman scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Postman data and credentials are handled as safely as possible.

Used by agents from

Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai
Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai
Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai

Never worry about agent reliability

We handle tool reliability, observability, and security so you never have to second-guess an agent action.

Book a call↗Get started for free