langchain-ai/lca-skills

langsmith-fetch

Fetches LangSmith traces for debugging agent behavior.

View source

How to use

  1. Copy the installation command and review the source package before installing it in your own agent environment.
  2. Check the source document for required tools, credentials and supported hosts.
  3. Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/langchain-ai/lca-skills --skill langsmith-fetch

Before you start

  • Installation does not include a model subscription, API allowance or permission to access your files.
  • Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document

Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.

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:

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

Commands

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

bash
# 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?

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