> ## Documentation Index > Fetch the complete documentation index at: https://docs.cloudthinker.io/llms.txt > Use this file to discover all available pages before exploring further. # LangSmith > Connect LangSmith so CloudThinker can find failed or costly LLM runs, inspect traces, and review dataset and experiment results. Connect a LangSmith workspace and ask [CloudThinker](https://docs.cloudthinker.io/guide/agents/overview.md) why an LLM run failed, which runs cost the most yesterday, or how two experiments compare on latency, cost, and feedback. You need three values: an API key, a workspace ID, and your region's API URL. ## Prerequisites * A LangSmith account with access to the workspace you want CloudThinker to read. * Permission to create an API key in LangSmith. Only organization admins can create service keys. * The **Admin** role in your CloudThinker workspace, which can add and edit connections. See [Roles](https://docs.cloudthinker.io/guide/security/roles.md). ## Setup **1. Create an API key** In LangSmith, open **Settings → API Keys**. Pick the key type from [Required permissions](#required-permissions). For a workspace-scoped service key, select the workspace. Set an expiration, then click **Create API Key**. **2. Copy the key** Copy the key now. LangSmith shows it only once. **3. Copy the workspace ID** If you belong to more than one workspace, switch to the one CloudThinker should read first. Then, on the **Settings** page, copy the **Workspace ID** under **General**. **4. Add the connection in CloudThinker** Open **More → Workspace settings → Connections**, stay on the **Builtin Connections** tab, and select **LangSmith**. Fill in all three fields from [Connection details](#connection-details), including your region's API URL, and click **Connect**. **Success state:** the LangSmith card shows **Connected**. > [!WARNING] > > **Connected** only means CloudThinker saved the connection. A bad key, workspace ID, or URL shows up only when CloudThinker first reads LangSmith, so run the [verify prompt](#verify-the-connection) before you rely on it. ## Connection details | Field | Required | Description | Example | | - | - | - | - | | **LANGSMITH\_API\_KEY** | Yes | Personal access token or service key from **Settings → API Keys** | `` | | **LANGSMITH\_WORKSPACE\_ID** | Yes | The workspace ID from **Settings → General** | `` | | **LANGSMITH\_ENDPOINT** | Yes | Your region's API URL, from the table below | `https://api.smith.langchain.com` | All three fields are required. LangSmith needs the workspace ID when a key covers more than one workspace, and it does no harm for a single-workspace key. | Region | API URL | | - | - | | GCP US (default) | `https://api.smith.langchain.com` | | GCP EU | `https://eu.api.smith.langchain.com` | | GCP APAC | `https://apac.api.smith.langchain.com` | | AWS US | `https://aws.api.smith.langchain.com` | For a self-hosted LangSmith, use that deployment's API URL. It must accept connections from the internet; behind a firewall, see [Reaching private services](https://docs.cloudthinker.io/guide/connections/overview.md#reaching-private-services). ## Required permissions | Key type | Who it acts as | Use it when | | - | - | - | | **Personal access token** | The user who created it, with all of that user's access | You're testing on your own | | **Service key, workspace-scoped** | Only the workspaces you pick | Recommended for a shared CloudThinker workspace | | **Service key, organization-scoped** | Every workspace in the organization | Avoid unless CloudThinker needs every workspace | > [!TIP] > > Create a workspace-scoped service key for the one workspace CloudThinker should read. On LangSmith Enterprise, give it the **Workspace Viewer** role for read-only access. Without a read-only role, the key can write, and only your Approvals settings decide whether a write runs without asking you. ## Agent capabilities | Capability | What you get | | - | - | | **Projects and runs** | Failed, slow, or costly runs in a named project, ranked by errors, latency, or cost | | **Traces and threads** | One trace, or the message history of a conversation thread | | **Datasets and examples** | Your datasets and the examples inside one dataset | | **Experiments** | Experiment results for a dataset, including latency, cost, and feedback | | **Prompts** | Your prompts and one prompt's template | CloudThinker summarizes what it finds. It doesn't print full run inputs, outputs, or message bodies, and it doesn't read LangSmith billing or usage data on this connection. ### Verify the connection ```text theme={null} List my LangSmith projects and datasets ``` **Success state:** you get project and dataset names that match your workspace in LangSmith. An empty list with no error is still a working connection: the workspace may just be empty. ### Example prompts Name the exact project or dataset. Ranking runs needs a project name, and experiments and examples need a dataset name. ```text theme={null} Show the five most expensive runs in the support-bot project from the last day and what drove their cost Find failed runs in the support-bot project and group them by error Compare the latest experiments on the support-eval dataset by latency, cost, and feedback ``` ## Write access CloudThinker reads by default. It writes only when you ask for that exact change by name in the conversation: pushing a prompt, creating or updating a dataset or its examples, or starting an experiment. Every change an agent makes goes through your workspace's [Approvals](https://docs.cloudthinker.io/guide/approvals/overview.md) first. On the default **Auto · Rules + AI · Ask me** mode, AI judgment can let a safe change run without asking — and an Allow Rule can too, once CloudThinker turns on [Rule enforcement](https://docs.cloudthinker.io/guide/approvals/rules.md#troubleshooting) for your workspace. Choose **Manual** to approve every change yourself. To rule out writes entirely, use a key with a read-only role (see [Required permissions](#required-permissions)). ## Troubleshooting > [accordion] 401 Unauthorized > > The key is missing, mistyped, expired, or deleted. Expired LangSmith keys can't be reactivated. Create a new key, then open **More → Workspace settings → Connections**, select **LangSmith**, and replace **LANGSMITH\_API\_KEY**. > [accordion] 403 Forbidden > > The key can't read that workspace. An organization-scoped key needs the right **LANGSMITH\_WORKSPACE\_ID**, and a workspace-scoped key only works for the workspaces you picked. Check both, plus the key's role. > [accordion] Requests fail or lists come back empty, but the key is right > > **LANGSMITH\_ENDPOINT** may not match your workspace's region. Set the endpoint to the URL for your region in [Connection details](#connection-details). > [accordion] 404, or a project or dataset isn't found > > The name doesn't exist in this workspace. Ask CloudThinker to list your projects or datasets first, then use an exact name. > [accordion] 429 Too Many Requests > > LangSmith limits how many requests a key can make per minute. Wait a minute, then ask a narrower question, for example one project and a shorter time window. ## Security * **Least privilege** — grant only the permissions the agents need for your use case; start read-only and widen later. * **Read-only by default** — use read-only credentials unless you want agents to make changes through this connection. * **Rotate credentials** — rotate keys and tokens on your normal schedule; CloudThinker picks up the new value when you update the connection. * **Revoke on offboarding** — remove the credential at the provider when you delete a connection or a teammate leaves. - **Workspace-scoped key**: limit the key to one workspace so others stay out of reach. - **Expiration**: set one on the key and replace the key before it lapses. ## Related > [card] [Langfuse](https://docs.cloudthinker.io/guide/connections/langfuse.md) > > Add LLM traces and prompts from Langfuse > [card] [Commands and Prompt Syntax](https://docs.cloudthinker.io/guide/commands.md) > > Point a question at one connection with # This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.