Can the agent place an outbound phone call for me?

Yes! Through the `createPhoneCallTool`, you can ask your agent: `Initiate a phone call to +15551234567 using our 'Sales Assistant' persona`. It will format the payload correctly and instruct Vapi to dial the human using the specified AI persona.

How can I read the transcript of an old automated voice call?

Just tell your chat assistant: `fetch the transcript details for call ID '3fbea5x...'`. The `getCallTool` reaches into Vapi, extracts the raw audio-to-text transcript logs, and the assistant can even summarize the entire human-to-AI interaction for you.

Can I tweak system prompts or models sequentially in my chat editor?

Yes, especially if you're in an IDE like Cursor. You can iterate: `Update Assistant 'Agent A' to use GPT-4o and set its prompt to 'Always be highly overly enthusiastic'`. The agent will use the `updateAssistantTool` to reconfigure the live voice persona instantly.

Vapi MCP Server for LangChain 10 tools — connect in under 2 minutes

Name: Vapi
Availability: InStock
Author: Vinkius

python.langchain.com/docs/integrations/tools/mcp

Built by Vinkius GDPR 10 Tools Framework

LangChain is the leading Python framework for composable LLM applications. Connect Vapi through the Vinkius and LangChain agents can call every tool natively — combine them with retrievers, memory, and output parsers for sophisticated AI pipelines.

Get MCP Server for AI Agents

ASK AI ABOUT THIS MCP SERVER

Open in ChatGPT Open in Claude Open in Perplexity

Vinkius supports streamable HTTP and SSE.

python

import asyncio
from langchain_mcp_adapters.client import MultiServerMCPClient
from langchain_openai import ChatOpenAI
from langgraph.prebuilt import create_react_agent

async def main():
    # Your Vinkius token — get it at cloud.vinkius.com
    async with MultiServerMCPClient({
        "vapi": {
            "transport": "streamable_http",
            "url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp",
        }
    }) as client:
        tools = client.get_tools()
        agent = create_react_agent(
            ChatOpenAI(model="gpt-4o"),
            tools,
        )
        response = await agent.ainvoke({
            "messages": [{
                "role": "user",
                "content": "Using Vapi, show me what tools are available.",
            }]
        })
        print(response["messages"][-1].content)

asyncio.run(main())

Fully ManagedVinkius Servers

60%Token savings

High SecurityEnterprise-grade

IAMAccess control

EU AI ActCompliant

DLPData protection

V8 IsolateSandboxed

Ed25519Audit chain

<40msKill switch

Stream every event to Splunk, Datadog, or your own webhook in real-time

* Every MCP server runs on Vinkius-managed infrastructure inside AWS - a purpose-built runtime with per-request V8 isolates, Ed25519 signed audit chains, and sub-40ms cold starts optimized for native MCP execution. See our infrastructure

About Vapi MCP Server

Connect your Vapi account to any AI agent and bring the power of automated voice communication into your standard conversational workspace.

LangChain's ecosystem of 500+ components combines seamlessly with Vapi through native MCP adapters. Connect 10 tools via the Vinkius and use ReAct agents, Plan-and-Execute strategies, or custom agent architectures — with LangSmith tracing giving full visibility into every tool call, latency, and token cost.

What you can do

Phone Calling — Send commands instructing the agent to place outbound human-like phone calls and establish web ringing connections through Vapi's PSTN/WebRTC capabilities.
Call Transcripts — Search through recent call logs, retrieve call details natively, and pull raw voice-to-text transcripts or conversation metrics.
Persona Engineering — Ask your chat agent to build new Vapi assistants, update their system prompts, change its specific model, or mutate Voice IDs on the fly.
Squad Routing — List available telephony numbers, tools, and multi-agent squads natively to configure advanced conversational pathways.

The Vapi MCP Server exposes 10 tools through the Vinkius. Connect it to LangChain in under two minutes — no API keys to rotate, no infrastructure to provision, no vendor lock-in. Your configuration, your data, your control.

How to Connect Vapi to LangChain via MCP

Follow these steps to integrate the Vapi MCP Server with LangChain.

Install dependencies

Run pip install langchain langchain-mcp-adapters langgraph langchain-openai

Replace the token

Replace [YOUR_TOKEN_HERE] with your Vinkius token

Run the agent

Save the code and run python agent.py

Explore tools

The agent discovers 10 tools from Vapi via MCP

Why Use LangChain with the Vapi MCP Server

LangChain provides unique advantages when paired with Vapi through the Model Context Protocol.

The largest ecosystem of integrations, chains, and agents — combine Vapi MCP tools with 500+ LangChain components

Agent architecture supports ReAct, Plan-and-Execute, and custom strategies with full MCP tool access at every step

LangSmith tracing gives you complete visibility into tool calls, latencies, and token usage for production debugging

Memory and conversation persistence let agents maintain context across Vapi queries for multi-turn workflows

Vapi + LangChain Use Cases

Practical scenarios where LangChain combined with the Vapi MCP Server delivers measurable value.

RAG with live data: combine Vapi tool results with vector store retrievals for answers grounded in both real-time and historical data

Autonomous research agents: LangChain agents query Vapi, synthesize findings, and generate comprehensive research reports

Multi-tool orchestration: chain Vapi tools with web scrapers, databases, and calculators in a single agent run

Production monitoring: use LangSmith to trace every Vapi tool call, measure latency, and optimize your agent's performance

Vapi MCP Tools for LangChain (10)

These 10 tools become available when you connect Vapi to LangChain via MCP:

create_assistant

Provide configuration for transcriber, model, and voice as a JSON string. Create a new Voice AI assistant persona

create_phone_call

Provide the phone number ID and customer details. Start a new outbound phone call via Vapi

create_web_call

Returns a web call configuration. Generate a new web-based voice call link

get_call_details

Retrieves details, transcripts, and metrics for a specific call

list_agent_tools

List all tools available to Vapi assistants

list_assistants

List all Voice AI assistants configured in Vapi

list_calls

List recent and active voice calls managed by Vapi

list_phone_numbers

List all phone numbers connected to Vapi

list_squads

List all multi-agent squads

update_assistant

Update an existing assistant configuration

Example Prompts for Vapi in LangChain

Ready-to-use prompts you can give your LangChain agent to start working with Vapi immediately.

"List all our configured Voice assistants and their IDs."

"Get the details and full transcript for call ID 'vapi1234'."

"Update assistant 'Bot Support' to change its `model.model` parameter to `gpt-4o-mini`."

Troubleshooting Vapi MCP Server with LangChain

Common issues when connecting Vapi to LangChain through the Vinkius, and how to resolve them.

MultiServerMCPClient not found

Install: pip install langchain-mcp-adapters

Vapi + LangChain FAQ

Common questions about integrating Vapi MCP Server with LangChain.

How does LangChain connect to MCP servers?

Use langchain-mcp-adapters to create an MCP client. LangChain discovers all tools and wraps them as native LangChain tools compatible with any agent type.

Which LangChain agent types work with MCP?

All agent types including ReAct, OpenAI Functions, and custom agents work with MCP tools. The tools appear as standard LangChain tools after the adapter wraps them.