langsmith-dataset

LANGSMITH_API_KEY=lsv2_pt_your_api_key_here          # REQUIRED
LANGSMITH_PROJECT=your-project-name                   # Check this to know which project has traces
LANGSMITH_WORKSPACE_ID=your-workspace-id              # Optional: for org-scoped keys

Authentication is REQUIRED: either set the LANGSMITH_API_KEY environment variable, or pass the --api-key flag to CLI commands (preferred):

langsmith dataset list --api-key $LANGSMITH_API_KEY

IMPORTANT: Always check the environment variables or .env file for LANGSMITH_PROJECT before querying or interacting with LangSmith. This tells you which project contains the relevant traces and data. If the LangSmith project is not available, use your best judgement to identify the right one.

Python Dependencies

pip

JavaScript Dependencies

CLI Tool

Dataset Commands

• langsmith dataset list - List datasets in LangSmith
• langsmith dataset get <name-or-id> - View dataset details
• langsmith dataset create --name <name> - Create a new empty dataset
• langsmith dataset delete <name-or-id> - Delete a dataset
• langsmith dataset export <name-or-id> <output-file> - Export dataset to local JSON file
• langsmith dataset upload <file> --name <name> - Upload a local JSON file as a dataset

Example Commands

• langsmith example list --dataset <name> - List examples in a dataset
• langsmith example create --dataset <name> --inputs <json> - Add an example to a dataset
• langsmith example delete <example-id> - Delete an example

Experiment Commands

• langsmith experiment list --dataset <name> - List experiments for a dataset
• langsmith experiment get <name> - View experiment results

Common Flags

• --limit N - Limit number of results
• --yes - Skip confirmation prompts (use with caution)

IMPORTANT - Safety Prompts:

• The CLI prompts for confirmation before destructive operations (delete, overwrite)
• If you are running with user input: ALWAYS wait for user input; NEVER use --yes unless the user explicitly requests it
• If you are running non-interactively: Use --yes to skip confirmation prompts

<dataset_types_overview> Common evaluation dataset types:

• final_response - Full conversation with expected output. Tests complete agent behavior.
• single_step - Single node inputs/outputs. Tests specific node behavior (e.g., one LLM call or tool).
• trajectory - Tool call sequence. Tests execution path (ordered list of tool names).
• rag - Question/chunks/answer/citations. Tests retrieval quality. </dataset_types_overview>

<creating_datasets>

Creating Datasets

Datasets are JSON files with an array of examples. Each example has inputs and outputs.

From Exported Traces (Programmatic)

Export traces first, then process them into dataset format using code:

client = Client()

2. Process traces into dataset examples

examples = [] for jsonl_file in Path("./traces").glob("*.jsonl"): runs = [json.loads(line) for line in jsonl_file.read_text().strip().split("\n")] root = next((r for r in runs if r.get("parent_run_id") is None), None) if root and root.get("inputs") and root.get("outputs"): examples.append({ "trace_id": root.get("trace_id"), "inputs": root["inputs"], "outputs": root["outputs"] })

3. Save locally

with open("/tmp/dataset.json", "w") as f: json.dump(examples, f, indent=2)

</python>
 
<typescript>
```typescript
import { Client } from "langsmith";
import { readFileSync, writeFileSync, readdirSync } from "fs";
import { join } from "path";
 
const client = new Client();
 
// 2. Process traces into dataset examples
const examples: Array<{trace_id?: string, inputs: Record<string, any>, outputs: Record<string, any>}> = [];
const files = readdirSync("./traces").filter(f => f.endsWith(".jsonl"));
 
for (const file of files) {
  const lines = readFileSync(join("./traces", file), "utf-8").trim().split("\n");
  const runs = lines.map(line => JSON.parse(line));
  const root = runs.find(r => r.parent_run_id == null);
  if (root?.inputs && root?.outputs) {
    examples.push({ trace_id: root.trace_id, inputs: root.inputs, outputs: root.outputs });
  }
}
 
// 3. Save locally
writeFileSync("/tmp/dataset.json", JSON.stringify(examples, null, 2));

Upload to LangSmith

Using the SDK Directly

client = Client()

Create dataset and add examples in one step

dataset = client.create_dataset("My Dataset", description="Evaluation dataset")

client.create_examples( inputs=[{"query": "What is AI?"}, {"query": "Explain RAG"}], outputs=[{"answer": "AI is..."}, {"answer": "RAG is..."}], dataset_name="My Dataset", )

</python>
 
<typescript>
```typescript
import { Client } from "langsmith";
 
const client = new Client();
 
// Create dataset and add examples
const dataset = await client.createDataset("My Dataset", {
  description: "Evaluation dataset",
});
 
await client.createExamples({
  inputs: [{ query: "What is AI?" }, { query: "Explain RAG" }],
  outputs: [{ answer: "AI is..." }, { answer: "RAG is..." }],
  datasetName: "My Dataset",
});

<dataset_structures>

Dataset Structures by Type

Final Response

Single Step

Trajectory

RAG

</dataset_structures>

<script_usage>

CLI Usage

</script_usage>

<example_workflow> Complete workflow from traces to uploaded LangSmith dataset:

</example_workflow>

Empty dataset after upload:

• Verify JSON file contains an array of objects with inputs key
• Check file isn't empty: langsmith example list --dataset "Name"

Export has no data:

• Ensure traces were exported with --full flag to include inputs/outputs
• Verify traces have both inputs and outputs populated

Example count mismatch:

• Use langsmith dataset get "Name" to check remote count
• Compare with local file to verify upload completeness