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Documentation Index

Fetch the complete documentation index at: https://docs.langchain.com/llms.txt

Use this file to discover all available pages before exploring further.

The LangSmith Remote MCP is a Model Context Protocol (MCP) server hosted by LangSmith. It exposes the same tools as the standalone LangSmith MCP Server (conversation history, prompts, runs and traces, datasets, experiments, billing) but with OAuth-based authentication, so MCP-compatible clients connect directly without an API key, a separate deployment, or any header configuration.
LangSmith Cloud (SaaS) only. The Remote MCP is available only on LangSmith Cloud (api.smith.langchain.com and eu.api.smith.langchain.com). Self-hosted LangSmith deployments should continue to use the standalone LangSmith MCP Server.

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Endpoints

RegionURL
Cloud (US)https://api.smith.langchain.com/mcp
Cloud (EU)https://eu.api.smith.langchain.com/mcp
The server discovers the rest of its OAuth metadata via RFC 8414 at /.well-known/oauth-authorization-server on the same host, so a compliant MCP client only needs the URL in the table.

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Authentication

Authentication uses OAuth 2.1 with Dynamic Client Registration (RFC 7591). Compatible MCP clients register themselves automatically on first use—there is no client ID to provision and no API key to manage. After registration:
  1. The client opens an authorization URL in your browser.
  2. You log in to LangSmith (or use an existing session) and consent.
  3. The client receives an access token and refresh token.
  4. The access token is automatically refreshed by the client when it expires.
The session is scoped to your LangSmith user and workspace permissions—calls through the MCP server can only view what your account is permitted to view.

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Quickstart

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Claude Code

Add the server to your project’s .mcp.json (or run claude mcp add --transport http -s user langsmith https://api.smith.langchain.com/mcp to install it user-wide): 
{
  "mcpServers": {
    "langsmith": {
      "type": "http",
      "url": "https://api.smith.langchain.com/mcp"
    }
  }
}
Then run /mcp and select langsmith to complete the OAuth flow. Tools become available as mcp__langsmith__<tool_name>.

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Cursor

Add to your Cursor mcp.json: 
{
  "mcpServers": {
    "LangSmith": {
      "url": "https://api.smith.langchain.com/mcp"
    }
  }
}
Cursor will prompt you to complete the OAuth flow on first use.

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Other clients

Any MCP client supporting the Streamable HTTP transport and OAuth 2.1 with dynamic client registration can connect with just the URL above.

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Known client incompatibilities

OpenAI Codex CLI does not work with the LangSmith Remote MCP. Codex omits the RFC 8707 resource parameter required by the MCP authorization spec during the OAuth flow, so login appears to succeed but the issued token is not bound to the LangSmith MCP and initialize fails with an auth-required error. Two upstream issues affect token exchange and authorize requests in Codex (refer to openai/codex#20729 and openai/codex#13891). In the meantime, use the LangSmith CLI from Codex—it supports the same projects, traces, runs, datasets, experiments, and threads as the MCP server, with native OAuth login.

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Available tools

The Remote MCP exposes the same tool surface as the standalone server:
  • Conversation and threads: get_thread_history
  • Prompt management: list_prompts, get_prompt_by_name, push_prompt
  • Traces and runs: fetch_runs, list_projects
  • Datasets and examples: list_datasets, list_examples, read_dataset, read_example, create_dataset, update_examples
  • Experiments and evaluations: list_experiments, run_experiment
  • Billing: get_billing_usage
See the standalone server reference for parameter and pagination details—both servers share the same tool implementations.

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Re-authenticating

If a client loses its session (for example, after revoking access in your LangSmith account, or if the refresh token is invalidated), trigger re-auth from the client:
  • Claude Code: run /mcp, select langsmith, choose re-authenticate.
  • Cursor: disable and re-enable the server in MCP settings.
  • Other clients: consult the client’s MCP settings UI.

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Self-hosted LangSmith

The Remote MCP is a SaaS-only feature, hosted alongside LangSmith Cloud—it is not yet available for self-hosted LangSmith deployments. To connect MCP clients to a self-hosted instance, run the standalone LangSmith MCP Server in your own environment and point its LANGSMITH_ENDPOINT at your self-hosted instance.
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