langsmith-fetch

Original：🇺🇸 English

Translated

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

2installs

Sourcelangchain-ai/lca-skills

Added on2026-04-03

NPX Install

npx skill4agent add langchain-ai/lca-skills langsmith-fetch

SKILL.md Content

View Translation Comparison →

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

Find

.env

:

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

Fetch recent traces:

uv run --env-file <path> langsmith-fetch traces ./debug --limit 10

Find relevant trace in saved JSON files
Check: What tools were called? What did they return? Was it correct/expected?