Connect MCP clients to a Managed Deep Agent

Managed Deep Agents deployments run on LangSmith Agent Server, so every deployment serves the Agent Server Model Context Protocol (MCP) endpoint at /mcp. Any MCP client that supports the Streamable HTTP transport can call the deployed agent as a tool, so another assistant or agent can delegate work to it without calling the deployment API directly. This page covers how to find the Managed Deep Agents URL and authenticate. For protocol behavior and generic Agent Server client setup, see MCP endpoint in Agent Server.

Managed Deep Agents is in public beta and available on LangSmith Cloud in the US region only.

The endpoint is the outbound direction. An MCP connector points the other way: it adds tools from a remote MCP server to your agent. A deployment can use both.

Find the endpoint URL

The endpoint is /mcp on the deployment’s API URL:

<DEPLOYMENT_API_URL>/mcp

mda deploy prints the LangSmith deployment dashboard URL, not the API URL. Open that dashboard, copy the API URL from the deployment details view, then append /mcp. The local server started by mda dev serves the same endpoint. Append /mcp to the local server URL the CLI prints.

Authenticate requests

The MCP endpoint uses the deployment’s identity configuration, the same as every other route on the deployment. Send the credential that matches the configured mode:

Identity mode	Header
LangSmith API key (default)	`x-api-key: <LANGSMITH_API_KEY>`
Supabase	`Authorization: Bearer <access_token>`

For the LangSmith API-key default, the key must belong to the workspace that owns the deployment. A key that is valid for another workspace is rejected. Authentication failures return one of three responses:

Status	Body	Cause
401	`{"detail":"missing x-api-key"}`	No credential header on the request.
403	`{"detail":"API key is forbidden"}`	The key is invalid, revoked, or expired.
403	`{"detail":"API key tenant mismatch"}`	The key is valid, but belongs to a different workspace than the deployment.

The local server started by mda dev requires no credential. It grants every caller an unscoped local service principal, so any client on the machine can call /mcp and every other route. Only a deployment enforces the header.

Anyone holding the LangSmith API key can reach the deployment, and an MCP client stores the header in its own configuration. Treat a key added to a client config as a shared secret for the whole workspace.

Supabase identity expects an access token that a person obtains by signing in to your app. An MCP client that stores only static headers cannot mint one, so use the LangSmith API-key default for deployments that MCP clients call.

Understand what the agent exposes

The Agent Server exposes the agent as an MCP tool:

Tool name: The agent name set in the agent definition.
Tool input schema: The agent’s input schema.

For transport details and other Agent Server MCP behavior, see MCP endpoint in Agent Server.

Add the agent to Claude Code

claude mcp add --transport http research-assistant \
  <DEPLOYMENT_API_URL>/mcp \
  --header "x-api-key: $LANGSMITH_API_KEY"

Claude Code lists the agent as a tool once the server connects. In a JSON configuration, Claude Code expands ${VAR} in header values, so the key stays in the environment instead of the config file:

"headers": { "x-api-key": "${LANGSMITH_API_KEY}" }

Add the agent to another MCP client

Clients that read an mcpServers configuration accept the endpoint and header directly:

{
  "mcpServers": {
    "research-assistant": {
      "type": "http",
      "url": "<DEPLOYMENT_API_URL>/mcp",
      "headers": {
        "x-api-key": "<LANGSMITH_API_KEY>"
      }
    }
  }
}

A client that accepts only a URL and negotiates OAuth cannot authenticate to the endpoint, which requires a header credential. Configure the header explicitly. Without one, a client may fall back to OAuth and report a Dynamic Client Registration failure rather than the missing header, which obscures the real cause.

Call the endpoint from code

Load the agent’s tool through an MCP client library, then pass the tools to a model or another agent:

import { MultiServerMCPClient } from "@langchain/mcp-adapters";

const client = new MultiServerMCPClient({
  mcpServers: {
    "research-assistant": {
      transport: "http",
      url: "<DEPLOYMENT_API_URL>/mcp",
      headers: { "x-api-key": process.env.LANGSMITH_API_KEY },
    },
  },
});

const tools = await client.getTools();

Read credentials from the environment. Do not hard-code them in client code.

Understand session behavior

Agent Server MCP requests are stateless: separate calls do not share thread state. To retain knowledge across calls, opt in to durable memory. Durable memory is optional and shared by every caller of the deployment. Do not enable it when MCP clients should not influence one another.

When to use the MCP endpoint

Concept	Kind	How it reaches the agent
MCP endpoint	Deployment API	Exposes the agent as a tool to MCP clients
MCP connectors	Managed configuration	Add tools hosted by remote MCP servers to the agent
Channels	Managed configuration	Receive messages from an external messaging service that start agent runs and deliver responses

Next steps

Agent Server

Explore the runtime that hosts every Managed Deep Agents deployment.

Agent Server MCP

Read the Agent Server MCP protocol reference.

MCP connectors

Add tools from remote MCP servers to the agent.

Identity

Authenticate callers to the deployment.

Connect these docs to Claude, VSCode, and more via MCP for real-time answers.

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Get started

Agent capabilities

Build and deploy

Connect MCP clients to a Managed Deep Agent

Find the endpoint URL

Authenticate requests

Understand what the agent exposes

Add the agent to Claude Code

Add the agent to another MCP client

Call the endpoint from code

Understand session behavior

When to use the MCP endpoint

Next steps

Agent Server

Agent Server MCP

MCP connectors

Identity

​Find the endpoint URL

​Authenticate requests

​Understand what the agent exposes

​Add the agent to Claude Code

​Add the agent to another MCP client

​Call the endpoint from code

​Understand session behavior

​When to use the MCP endpoint

​Next steps

Agent Server

Agent Server MCP

MCP connectors

Identity

Find the endpoint URL

Authenticate requests

Understand what the agent exposes

Add the agent to Claude Code

Add the agent to another MCP client

Call the endpoint from code

Understand session behavior

When to use the MCP endpoint

Next steps