Langsmith MCP Server

A **hosted version** of the LangSmith MCP Server is available over HTTP-streamable transport, so you can connect without running the server yourself:

Remote serverstreamable-httpPython

What is the Langsmith MCP server?

Langsmith MCP server is a hosted integration for AI assistants that speak the Model Context Protocol. A hosted version of the LangSmith MCP Server is available over HTTP-streamable transport, so you can connect without running the server yourself:.

What the assistant can call

Once Langsmith is connected, these are the calls the assistant has available:

  • get_billing_usage — Fetch organization billing usage (e.g. trace counts) for a date range. Optional workspace filter; returns metrics with workspace names inline
  • Prerequisites — The Prerequisites tool exposed by this server
  • Setup — uv sync # Install dependencies uv sync --group test # Include test dependencies (pytest, ruff, mypy)

Setting it up

Being a remote server, there is no local install. You register the endpoint with your client, authorise it once, and the tools appear.

Configuration and credentials

You will need 5 environment variables: LANGSMITH_API_KEY, LANGSMITH_WORKSPACE_ID, LANGSMITH_ENDPOINT, LANGSMITH_MONITORING_API_KEY, LANGSMITH_MONITORING_WORKSPACE_ID. The server will not start without them, which is usually why the tools fail to appear on a first run. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

  • Python 3.10+ (3.11+ recommended) - uv – install with curl -LsSf https://astral.sh/uv/install.sh | sh - LangSmith API key – from smith.langchain.com - Node.js (optional) – only if you want to use MCP Inspector to test the server (stdio or streamable-http)

Choosing this one

Among the developer tooling options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. Langsmith's toolset — get_billing_usage, Prerequisites, Setup — is a fair guide to whether it matches your workflow. It is maintained by langchain-ai; worth a glance at recent repository activity before you build anything load-bearing on it.

SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.

Before you rely on it

  • Your data travels to the provider's service, so the usual questions apply about what you send and what they retain.
  • Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
  • MCP clients confirm each tool call by default. Leave that on until you have watched what the langsmith mcp server does with a few real requests.

Available tools

ToolWhat it does
get_billing_usageFetch organization billing usage (e.g. trace counts) for a date range. Optional workspace filter; returns metrics with workspace names inline.
PrerequisitesThe Prerequisites tool exposed by this server.
Setupuv sync # Install dependencies uv sync --group test # Include test dependencies (pytest, ruff, mypy)

How to install the Langsmith MCP server

{
  "mcpServers": {
    "LangSmith MCP (Hosted)": {
      "url": "https://langsmith-mcp-server.onrender.com/mcp",
      "headers": {
        "LANGSMITH-API-KEY": "lsv2_pt_your_api_key_here"
      }
    }
  }
}

Configuration as documented by the project. Restart the client after saving.

Configuration

  • Python 3.10+ (3.11+ recommended) - uv – install with curl -LsSf https://astral.sh/uv/install.sh | sh - LangSmith API key – from smith.langchain.com - Node.js (optional) – only if you want to use MCP Inspector to test the server (stdio or streamable-http)
VariableDescriptionRequired
LANGSMITH_API_KEYCredential the server authenticates with.Yes
LANGSMITH_WORKSPACE_IDConfiguration value read at startup.Optional
LANGSMITH_ENDPOINTConfiguration value read at startup.Optional
LANGSMITH_MONITORING_API_KEYCredential the server authenticates with.Yes
LANGSMITH_MONITORING_WORKSPACE_IDConfiguration value read at startup.Optional

Example prompts to try

  • Use Langsmith to get billing usage.
  • Use Langsmith to Prerequisites.
  • Use Langsmith to Setup.

Frequently asked questions

It connects Langsmith to MCP-compatible AI assistants such as Claude and Cursor, exposing 3 tools (get_billing_usage, Prerequisites, Setup) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with Langsmith directly.