LangSmith/MCP/Remote
Properties
- created-by
- LangChain
- MCP server hosted by LangSmith itself, so there is nothing to deploy: point a client at
https://api.smith.langchain.com/mcp (or the EU, APAC, and AWS regional hosts). - Supersedes the self-deployed LangSmith/MCP/Server, which is now deprecated, and exposes the same tool surface:
get_thread_history, list_prompts, get_prompt_by_name, push_prompt, fetch_runs, list_projects, list_datasets, list_examples, read_dataset, read_example, create_dataset, update_examples, list_experiments, run_experiment, get_billing_usage. - Interactive clients authenticate over OAuth 2.1 with dynamic client registration (RFC 7591) — no client ID to provision and no API key to manage. Programmatic clients send a LangSmith API key in the
X-Api-Key header instead; the deprecated standalone server used LANGSMITH-API-KEY. - Sessions are scoped to the calling user's LangSmith workspace permissions, so a tool call can only read what that account can read.
- Speaks the Streamable HTTP transport and is stateless, so any compliant client connects with the URL alone. Large payloads use character-budget pagination (
page_number, total_pages, max_chars_per_page) rather than cursors. - OpenAI's Codex CLI cannot use it: Codex omits the RFC 8707
resource parameter during the OAuth flow, so login appears to succeed but initialize fails with an auth error (openai/codex#20729). - Self-hosted LangSmith v0.16+ serves it at
https://<host>/api/mcp, but it stays inert (404) until an Ed25519 signing JWKS is supplied as config.signingJwks.