LangSmith

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At a glance

• Availability: Experimental (how to enable).
• Authentication: API key.
• Connection: The key from LANGSMITH_API_KEY is sent as the x-api-key header.
• Provider documentation: Authentication reference.

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Credentials

Set these per environment. See Connect an integration.

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Setup

1. Create a LangSmith account: Sign up at https://smith.langchain.com - the free Developer plan includes traces for testing.
2. Create an API key: In LangSmith go to Settings → API Keys and create a key (Personal Access Token or Service Key). Copy it immediately - it is only shown once.
3. Store the key: Add it to your .env file as LANGSMITH_API_KEY=lsv2_…
4. Verify access: Run the List Projects tool. If you belong to multiple workspaces, make sure the key was created in the workspace you want to query.

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Provider notes

• API keys are workspace-scoped; data from other workspaces is not visible to the key
• EU-region organizations use https://eu.api.smith.langchain.com - these tools target the default US endpoint
• Query Runs filter expressions are documented at https://docs.langchain.com/langsmith/trace-query-syntax

Provider API reference.

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Tools

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Verify the connection

Call a read tool such as langsmith__list_projects with arguments for your account. Confirm that the result comes from the intended account or workspace before enabling write tools.