---
title: "Vercel AI SDK (TypeScript)"
url: "/docs/proxy/lens/integrations/vercel-ai-sdk-js"
canonical_url: "https://docs.litellm.ai/docs/proxy/lens/integrations/vercel-ai-sdk-js"
type: "docs"
last_updated: "2026-10-03"
summary: "Run Vercel AI SDK (TypeScript) examples and send their agent traces to LiteLLM Lens."
related:
  - "/docs/proxy/lens/integrations/strands"
  - "/docs/proxy/lens/integrations/vercel-ai-sdk-py"
---
# Vercel AI SDK (TypeScript)

> Index of all LiteLLM docs: https://docs.litellm.ai/llms.txt

<!-- Generated from BerriAI/litellm-lens-example/vercel-ai-sdk-js/README.md at a6cce7983ec78ef9183627a0b05e0e3ce548b98a. Edit the source README. -->

# Vercel AI SDK (TypeScript)

Send Vercel AI SDK (TypeScript) traces to [LiteLLM Lens](/docs/proxy/lens) using the runnable examples in this repository.

## Prerequisites

You need a LiteLLM gateway with [tracing enabled](/docs/proxy/lens/deployment#configure-an-existing-proxy), a LiteLLM key, and a configured model alias. The swarm example needs a model that supports tool calls. A Lens worker is required for investigations; viewing traces does not require one.

Use Node.js with built-in TypeScript support and npm. Install dependencies from the repository root so the shared npm workspaces are available.

## Configuration

For a fresh checkout:

```bash
git clone https://github.com/BerriAI/litellm-lens-example.git
cd litellm-lens-example
npm install
cd vercel-ai-sdk-js
cp .env.example .env
```

If you already cloned the repository, run the remaining commands from `vercel-ai-sdk-js/`. Run `npm install` from the repository root if you have not installed the workspace dependencies. Copy [.env.example](https://github.com/BerriAI/litellm-lens-example/blob/a6cce7983ec78ef9183627a0b05e0e3ce548b98a/vercel-ai-sdk-js/.env.example) to `.env` if it does not exist, then set:

| Variable              | Value                                                                                          |
| --------------------- | ---------------------------------------------------------------------------------------------- |
| `LITELLM_GATEWAY_URL` | Your gateway’s base URL without a trailing slash or `/v1`, for example `http://localhost:4002` |
| `LITELLM_API_KEY`     | Your LiteLLM key                                                                               |
| `LITELLM_MODEL`       | A model alias configured on your gateway                                                       |

The checked-in values target a local development gateway. Replace them for your deployment. Keep the exporter settings from `.env.example`; the examples configure their trace exporters in code. They send traces to `LITELLM_GATEWAY_URL/v1/traces` with the LiteLLM key as a bearer token.

Leave `MOCK_LITELLM_GATEWAY_URL` unset unless you intend to send an additional trace copy to the local [recorder](https://github.com/BerriAI/litellm-lens-example/blob/a6cce7983ec78ef9183627a0b05e0e3ce548b98a/recorder/AGENTS.md).

## Run an example

### Simple agent

A `generateText` call is traced as `research_agent`.

```bash
node --env-file=.env simple/main.ts
```

See [simple/main.ts](https://github.com/BerriAI/litellm-lens-example/blob/a6cce7983ec78ef9183627a0b05e0e3ce548b98a/vercel-ai-sdk-js/simple/main.ts) for the implementation.

### Agent swarm

A coordinator delegates through tools that run `generateText` as `search_agent` and `writer_agent`.

```bash
node --env-file=.env swarm/main.ts
```

See [swarm/main.ts](https://github.com/BerriAI/litellm-lens-example/blob/a6cce7983ec78ef9183627a0b05e0e3ce548b98a/vercel-ai-sdk-js/swarm/main.ts) for the implementation.

## Verify the trace

After the example prints its answer, open **Lens > Traces** on your gateway and select the new run. Look for the run associated with `research_agent`. Inspect the input, output, and model spans. For the swarm, inspect the specialist activity described above; its exact span layout depends on the framework.

## How tracing works

The @ai-sdk/otel integration creates OpenTelemetry spans and the NodeSDK exports them to LiteLLM. The example names agent spans from functionId. The shared gateway fetch records request attempts and gateway call IDs.

See the [shared gateway transport](https://github.com/BerriAI/litellm-lens-example/blob/a6cce7983ec78ef9183627a0b05e0e3ce548b98a/shared/README.md) for request-attempt and spend-correlation details.

## Troubleshooting

If model calls fail, check the gateway URL, key, and model alias. If an answer appears but the trace is missing, check the terminal for exporter errors and confirm tracing is enabled on the same gateway. A model call succeeding does not confirm that its trace export succeeded.

## Transport validation

Run the shared transport regressions from this folder:

```bash
npm test -w gateway-tracing
```

Validate real gateway streaming, retry, and billed response loss with:

```bash
node --env-file=.env validate-attempts.ts streaming
node --env-file=.env validate-attempts.ts retry
node --env-file=.env validate-attempts.ts response-loss
```

The retry scenario replaces the first real billed response with a client-side HTTP 503. The response-loss scenario consumes the real billed response and fails the client stream. Neither scenario changes gateway or provider behavior.

## Related pages

- [Strands Agents](https://docs.litellm.ai/docs/proxy/lens/integrations/strands.md)
- [Vercel AI SDK (Python)](https://docs.litellm.ai/docs/proxy/lens/integrations/vercel-ai-sdk-py.md)