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Claude Cowork runs the same plugins as Claude Code, so the LangSmith tracing plugin for Claude Code also traces Cowork tasks. Each turn becomes a trace, and a task’s turns are grouped into a thread.

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Prerequisites

  • Access to Claude Cowork in the Claude desktop app.
  • A LangSmith account.

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Install the plugin

Cowork installs plugins from your claude.ai account. To install the plugin for yourself:
  1. Go to Customize > Plugins on claude.ai.
  2. Add langchain-ai/langsmith-claude-code-plugins or https://github.com/langchain-ai/langsmith-claude-code-plugins as a marketplace.
  3. Install the langsmith-tracing plugin from that marketplace.
The plugin loads into the next Cowork task you start. To install it for everyone see Deploy to your organization. For more on installing plugins, see Cowork plugins in the Claude docs.

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Sign in

Sign in once with the LangSmith CLI. See Install the LangSmith CLI if you do not have it yet.
If you use the CLI sign-in and have more than one profile, set profile in your config file to the one the plugin should use. Your own api_key ignores this setting, but a generic LANGSMITH_API_KEY is not used as a fallback while profile is set. To use an API key instead, add it to ~/.claude/langsmith.json, the same file Claude Code reads:
If more than one credential is set, the plugin uses the first one it finds:
  1. The plugin’s own key from api_key or CC_LANGSMITH_API_KEY.
  2. Your langsmith auth login sign-in.
  3. A generic LANGSMITH_API_KEY from your environment.
Tracing stops when your sign-in expires or your key is rejected, and turns from that gap are never uploaded. Admins can also require a working sign-in for every prompt.

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Turn on tracing

Tracing is off until you turn it on in ~/.claude/langsmith.json, unless your admin already turned it on with a managed file. Send traces to an agent with agent_id:
Or send them to a project with project:
Use either one. If you set both, agent_id wins. Start a Cowork task and open your agent or project in LangSmith. Skill calls record which skill ran, so you can filter traces by skill.

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Deploy to your organization

Admins can install the plugin for everyone and control how it traces from one place.

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Install for everyone

Organization owners can add the plugin to every member’s claude.ai account, so it reaches Cowork and Claude Code together. For the setup, see Choose a rollout route.

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Lock settings

An admin can lock tracing settings for every user with a managed file at ~/.langsmith-plugins/managed.json in each user’s home folder. The Claude Code, Cursor, and Codex plugins all read this file, and its settings override the user’s own config files and environment variables.
The managed file works on macOS and Linux. The plugin only trusts it when:
  • Root owns the file and its folder.
  • No other user can write to either.
  • Neither is a symlink.
If the file exists but fails these checks, tracing stops and the user sees a message to contact their admin. Locking a setting also locks the settings tied to it, so users cannot route traces around the lock. For example, locking project also stops users from adding their own replicas or sending traces to an agent with agent_id. Admins usually install the file on each machine with a mobile device management (MDM) tool such as Jamf or Microsoft Intune. For every setting you can lock, see the plugin settings guide.
Run this as root for each user, with USER_HOME set to that user’s home folder:
On Linux, use root:root instead of root:wheel. For the full script, see Set it up on macOS.

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Require a working sign-in

Strict auth blocks every prompt until the user’s sign-in or key works, so no session goes untraced. It is off by default and has no effect while tracing is off. To turn it on for everyone, set strict_auth to true in the managed file.

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Hide a conversation

Run /langsmith-tracing:mute in a Cowork task to keep its content out of LangSmith, and /langsmith-tracing:unmute to turn it back on. To mute every task by default, set defaultMuted to true.

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Secret redaction

The plugin strips secrets on your machine before anything is uploaded, so they never reach LangSmith or a replica. Redaction is on by default. It catches provider API keys, JSON Web Tokens, and PEM private keys, along with common patterns such as API_KEY=<value> or a password in a URL. Each match is replaced with [SECRET_DETECTED]. For the full rule list, see Redact secrets from traces. Redaction only matches known credential shapes, so treat it as a safety net rather than a guarantee. Run names, tags, and attachments skip it, and a redacted trace still holds your prompts and file contents. Limit who can read the tracing project.

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Settings

Cowork uses the same settings as Claude Code. For the main ones, see Settings. For every setting, see the plugin settings.
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