Borrowing it
Nothing to install: this file belongs to langchain-ai/langsmith-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/langchain-ai/langsmith-mcp-server/main/CLAUDE.mdgit clone --depth 1 https://github.com/langchain-ai/langsmith-mcp-serverWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/langchain-ai/langsmith-mcp-server/claude-md)<a href="https://agentmods.dev/instructions/langchain-ai/langsmith-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/langchain-ai/langsmith-mcp-server/claude-md.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.06401 | $0.06401 |
| Opus 5 | $0.03200 | $0.03200 |
| Sonnet 5 | $0.01280 | $0.01280 |
| Haiku 4.5 | $0.00640 | $0.00640 |
Grade A, and why
langsmith-mcp-server CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 653 lines — stays where its author put it; the contents beside it link to each section on GitHub.
LangSmith MCP Server - Technical Reference & Development Guide
⚠️ IMPORTANT: Keeping This Document Updated
When you make changes to this codebase, please update this CLAUDE.md file if:
- You add or remove MCP tools
- You modify the architecture or add new modules
- You change configuration requirements or setup procedures
- You add new dependencies or change build processes
- You discover important patterns or best practices
This document serves as the primary context for AI assistants working on this project. Keeping it accurate ensures efficient development.
Project Overview
The LangSmith MCP Server is a production-ready Model Context Protocol (MCP) server that provides seamless integration with the LangSmith observability platform. This server enables AI language models to programmatically interact with LangSmith's suite of tools for conversation tracking, prompt management, dataset operations, and trace analytics.
What is LangSmith?
LangSmith is LangChain's comprehensive observability and evaluation platform for LLM applications, providing:
- Conversation thread tracking and history
- Prompt template management and versioning
- Dataset creation and management for testing
- Trace collection and analysis for debugging
- Performance analytics and monitoring
- Billing and usage tracking
What is MCP?
The Model Context Protocol (MCP) is an open standard that enables secure connections between AI assistants and external data sources and tools. This server implements the MCP specification to bridge AI models with LangSmith's capabilities.
Architecture Deep Dive
Core Components
1. Server Architecture (server.py)
The server is built on FastMCP, a high-performance MCP framework that provides:
- Transport Layer: Uses stdio transport for CLI/desktop integration, HTTP for web-based access
- Tool Registration: Modular system for registering LangSmith tools via
register_tools() - Middleware Stack: API key authentication and CORS handling
- Error Handling: Comprehensive exception handling across all operations
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 653 lines · 6,401 tokens per session scan A 17e4792f502e
langsmith-mcp-server CLAUDE.md is an instructions file published in the GitHub repository langchain-ai/langsmith-mcp-server (131 stars, last pushed 27d ago), licensed MIT. It adds 6,401 tokens to every session, about $0.0320 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.