How to integrate Postman MCP with LlamaIndex

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Introduction

This guide walks you through connecting Postman to LlamaIndex 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 LlamaIndex 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:
  • Set your OpenAI and Composio API keys
  • Install LlamaIndex and Composio packages
  • Create a Composio Tool Router session for Postman
  • Connect LlamaIndex to the Postman MCP server
  • Build a Postman-powered agent using LlamaIndex
  • Interact with Postman through natural language

What is LlamaIndex?

LlamaIndex is a data framework for building LLM applications. It provides tools for connecting LLMs to external data sources and services through agents and tools.

Key features include:

  • ReAct Agent: Reasoning and acting pattern for tool-using agents
  • MCP Tools: Native support for Model Context Protocol
  • Context Management: Maintain conversation context across interactions
  • Async Support: Built 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 you begin, make sure you have:
  • Python 3.8/Node 16 or higher installed
  • A Composio account with the API key
  • An OpenAI API key
  • A Postman account and project
  • Basic familiarity with async Python/Typescript

Getting API Keys for OpenAI, Composio, and Postman

OpenAI API key (OPENAI_API_KEY)
  • Go to the OpenAI dashboard
  • Create an API key if you don't have one
  • Assign it to OPENAI_API_KEY in .env
Composio API key and user ID
  • Log into the Composio dashboard
  • Copy your API key from Settings
    • Use this as COMPOSIO_API_KEY
  • Pick a stable user identifier (email or ID)
    • Use this as COMPOSIO_USER_ID

Installing dependencies

pip install composio-llamaindex llama-index llama-index-llms-openai llama-index-tools-mcp python-dotenv

Create a new Python project and install the necessary dependencies:

  • composio-llamaindex: Composio's LlamaIndex integration
  • llama-index: Core LlamaIndex framework
  • llama-index-llms-openai: OpenAI LLM integration
  • llama-index-tools-mcp: MCP client for LlamaIndex
  • python-dotenv: Environment variable management

Set environment variables

bash
OPENAI_API_KEY=your-openai-api-key
COMPOSIO_API_KEY=your-composio-api-key
COMPOSIO_USER_ID=your-user-id

Create a .env file in your project root:

These credentials will be used to:

  • Authenticate with OpenAI's GPT-5 model
  • Connect to Composio's Tool Router
  • Identify your Composio user session for Postman access

Import modules

import asyncio
import os
import dotenv

from composio import Composio
from composio_llamaindex import LlamaIndexProvider
from llama_index.core.agent.workflow import ReActAgent
from llama_index.core.workflow import Context
from llama_index.llms.openai import OpenAI
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec

dotenv.load_dotenv()

Create a new file called postman_llamaindex_agent.py and import the required modules:

Key imports:

  • asyncio: For async/await support
  • Composio: Main client for Composio services
  • LlamaIndexProvider: Adapts Composio tools for LlamaIndex
  • ReActAgent: LlamaIndex's reasoning and action agent
  • BasicMCPClient: Connects to MCP endpoints
  • McpToolSpec: Converts MCP tools to LlamaIndex format

Load environment variables and initialize Composio

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not OPENAI_API_KEY:
    raise ValueError("OPENAI_API_KEY is not set in the environment")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set in the environment")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set in the environment")

What's happening:

This ensures missing credentials cause early, clear errors before the agent attempts to initialise.

Create a Tool Router session and build the agent function

async def build_agent() -> ReActAgent:
    composio_client = Composio(
        api_key=COMPOSIO_API_KEY,
        provider=LlamaIndexProvider(),
    )

    session = composio_client.create(
        user_id=COMPOSIO_USER_ID,
        toolkits=["postman"],
    )

    mcp_url = session.mcp.url
    print(f"Composio MCP URL: {mcp_url}")

    mcp_client = BasicMCPClient(mcp_url, headers={"x-api-key": COMPOSIO_API_KEY})
    mcp_tool_spec = McpToolSpec(client=mcp_client)
    tools = await mcp_tool_spec.to_tool_list_async()

    llm = OpenAI(model="gpt-5")

    description = "An agent that uses Composio Tool Router MCP tools to perform Postman actions."
    system_prompt = """
    You are a helpful assistant connected to Composio Tool Router.
    Use the available tools to answer user queries and perform Postman actions.
    """
    return ReActAgent(tools=tools, llm=llm, description=description, system_prompt=system_prompt, verbose=True)

What's happening here:

  • We create a Composio client using your API key and configure it with the LlamaIndex provider
  • We then create a tool router MCP session for your user, specifying the toolkits we want to use (in this case, postman)
  • The session returns an MCP HTTP endpoint URL that acts as a gateway to all your configured tools
  • LlamaIndex will connect to this endpoint to dynamically discover and use the available Postman tools.
  • The MCP tools are mapped to LlamaIndex-compatible tools and plug them into the Agent.

Create an interactive chat loop

async def chat_loop(agent: ReActAgent) -> None:
    ctx = Context(agent)
    print("Type 'quit', 'exit', or Ctrl+C to stop.")

    while True:
        try:
            user_input = input("\nYou: ").strip()
        except (KeyboardInterrupt, EOFError):
            print("\nBye!")
            break

        if not user_input or user_input.lower() in {"quit", "exit"}:
            print("Bye!")
            break

        try:
            print("Agent: ", end="", flush=True)
            handler = agent.run(user_input, ctx=ctx)

            async for event in handler.stream_events():
                # Stream token-by-token from LLM responses
                if hasattr(event, "delta") and event.delta:
                    print(event.delta, end="", flush=True)
                # Show tool calls as they happen
                elif hasattr(event, "tool_name"):
                    print(f"\n[Using tool: {event.tool_name}]", flush=True)

            # Get final response
            response = await handler
            print()  # Newline after streaming
        except KeyboardInterrupt:
            print("\n[Interrupted]")
            continue
        except Exception as e:
            print(f"\nError: {e}")

What's happening here:

  • We're creating a direct terminal interface to chat with your Postman database
  • The LLM's responses are streamed to the CLI for faster interaction.
  • The agent uses context to maintain conversation history
  • You can type 'quit' or 'exit' to stop the chat loop gracefully
  • Agent responses and any errors are displayed in a clear, readable format

Define the main entry point

async def main() -> None:
    agent = await build_agent()
    await chat_loop(agent)

if __name__ == "__main__":
    # Handle Ctrl+C gracefully
    signal.signal(signal.SIGINT, lambda s, f: (print("\nBye!"), exit(0)))
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("\nBye!")

What's happening here:

  • We're orchestrating the entire application flow
  • The agent gets built with proper error handling
  • Then we kick off the interactive chat loop so you can start talking to Postman

Run the agent

npx ts-node llamaindex-agent.ts

When prompted, authenticate and authorise your agent with Postman, then start asking questions.

Complete Code

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

import asyncio
import os
import signal
import dotenv

from composio import Composio
from composio_llamaindex import LlamaIndexProvider
from llama_index.core.agent.workflow import ReActAgent
from llama_index.core.workflow import Context
from llama_index.llms.openai import OpenAI
from llama_index.tools.mcp import BasicMCPClient, McpToolSpec

dotenv.load_dotenv()

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
COMPOSIO_API_KEY = os.getenv("COMPOSIO_API_KEY")
COMPOSIO_USER_ID = os.getenv("COMPOSIO_USER_ID")

if not OPENAI_API_KEY:
    raise ValueError("OPENAI_API_KEY is not set")
if not COMPOSIO_API_KEY:
    raise ValueError("COMPOSIO_API_KEY is not set")
if not COMPOSIO_USER_ID:
    raise ValueError("COMPOSIO_USER_ID is not set")

async def build_agent() -> ReActAgent:
    composio_client = Composio(
        api_key=COMPOSIO_API_KEY,
        provider=LlamaIndexProvider(),
    )

    session = composio_client.create(
        user_id=COMPOSIO_USER_ID,
        toolkits=["postman"],
    )

    mcp_url = session.mcp.url
    print(f"Composio MCP URL: {mcp_url}")

    mcp_client = BasicMCPClient(mcp_url, headers={"x-api-key": COMPOSIO_API_KEY})
    mcp_tool_spec = McpToolSpec(client=mcp_client)
    tools = await mcp_tool_spec.to_tool_list_async()

    llm = OpenAI(model="gpt-5")
    description = "An agent that uses Composio Tool Router MCP tools to perform Postman actions."
    system_prompt = """
    You are a helpful assistant connected to Composio Tool Router.
    Use the available tools to answer user queries and perform Postman actions.
    """
    return ReActAgent(
        tools=tools,
        llm=llm,
        description=description,
        system_prompt=system_prompt,
        verbose=True,
    );

async def chat_loop(agent: ReActAgent) -> None:
    ctx = Context(agent)
    print("Type 'quit', 'exit', or Ctrl+C to stop.")

    while True:
        try:
            user_input = input("\nYou: ").strip()
        except (KeyboardInterrupt, EOFError):
            print("\nBye!")
            break

        if not user_input or user_input.lower() in {"quit", "exit"}:
            print("Bye!")
            break

        try:
            print("Agent: ", end="", flush=True)
            handler = agent.run(user_input, ctx=ctx)

            async for event in handler.stream_events():
                # Stream token-by-token from LLM responses
                if hasattr(event, "delta") and event.delta:
                    print(event.delta, end="", flush=True)
                # Show tool calls as they happen
                elif hasattr(event, "tool_name"):
                    print(f"\n[Using tool: {event.tool_name}]", flush=True)

            # Get final response
            response = await handler
            print()  # Newline after streaming
        except KeyboardInterrupt:
            print("\n[Interrupted]")
            continue
        except Exception as e:
            print(f"\nError: {e}")

async def main() -> None:
    agent = await build_agent()
    await chat_loop(agent)

if __name__ == "__main__":
    # Handle Ctrl+C gracefully
    signal.signal(signal.SIGINT, lambda s, f: (print("\nBye!"), exit(0)))
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("\nBye!")

Conclusion

You've successfully connected Postman to LlamaIndex through Composio's Tool Router MCP layer. Key takeaways:
  • Tool Router dynamically exposes Postman tools through an MCP endpoint
  • LlamaIndex's ReActAgent handles reasoning and orchestration; Composio handles integrations
  • The agent becomes more capable without increasing prompt size
  • Async Python provides clean, efficient execution of agent workflows
You can easily extend this to other toolkits like Gmail, Notion, Stripe, GitHub, and more by adding them to the toolkits parameter.

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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 LlamaIndex?

Yes, you can. LlamaIndex 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.

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