MCPInstall

langsmith-fetch

by langchain-ai OfficialAI & Agents

Fetches LangSmith traces for debugging agent behavior. Use when troubleshooting agent issues, reviewing conversation history, or investigating tool calls.

Installs
899
Last 24h
+16
Trending rank
#6729
Security
Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/langchain-ai/lca-skills --skill langsmith-fetch
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads langsmith-fetch automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Fetching LangSmith Traces

Requires langsmith-fetch in project dependencies and LANGSMITH_API_KEY in a .env file.

Setup

First, find the .env file containing LANGSMITH_API_KEY:

find . -name ".env" -type f 2>/dev/null | head -5

Commands

Use --env-file <path-to-.env> with all commands:

# Fetch recent traces (uses LANGSMITH_PROJECT from .env, or specify --project-uuid)
uv run --env-file <path> langsmith-fetch traces ./traces --limit 10
uv run --env-file <path> langsmith-fetch traces ./traces --project-uuid <uuid> --limit 10

# Fetch single trace by ID
uv run --env-file <path> langsmith-fetch trace <trace-id>

# Include metadata (timing, tokens, costs)
uv run --env-file <path> langsmith-fetch trace <trace-id> --include-metadata

Output Formats

  • --format pretty - Human-readable (default)
  • --format json - Pretty-printed JSON
  • --format raw - Compact JSON for piping

Troubleshooting Workflow

  1. Find .env: find . -name ".env" -type f 2>/dev/null
  2. Fetch recent traces: uv run --env-file <path> langsmith-fetch traces ./debug --limit 10
  3. Find relevant trace in saved JSON files
  4. Check: What tools were called? What did they return? Was it correct/expected?

FAQ

What does the langsmith-fetch skill do?

Fetches LangSmith traces for debugging agent behavior. Use when troubleshooting agent issues, reviewing conversation history, or investigating tool calls.

How do I install langsmith-fetch?

Run npx skills add https://github.com/langchain-ai/lca-skills --skill langsmith-fetch in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/langsmith-fetch/ (personal) or .claude/skills/langsmith-fetch/ (project).

Which AI agents can use langsmith-fetch?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is langsmith-fetch safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains langsmith-fetch?

It is published by langchain-ai in langchain-ai/lca-skills, and it is an official skill from the maker of the technology it covers. It has 899 recorded installs.

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