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A conditional rule is a field control that matches on a value in the data rather than on a field path. For example, it can remove Google Drive files labeled Confidential from search results, or block agents from posting to an externally shared Slack channel. Unlike a field-path rule, a conditional rule applies to every tool on the server you select — there is no per-tool scoping.

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Supported servers

Conditional rules are available for these Barndoor-hosted MCP servers from the MCP server directory:

Google Drive

Match files by their Google Drive labels and label options.

Slack

Match messages and posts by channel or channel type.
Add Conditional Rule is unavailable until your organization has a Slack (User) or Google Drive server.

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Before you start

Connect the server’s service account — the organization-level OAuth connection on the server detail page. Barndoor uses it to list live values, such as your Drive labels or Slack channels, while you build a rule. If it isn’t connected, the rule dialog prompts you to connect it.

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Rule settings

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How Applies to and Then combine

Applies to options All tools, Read, and Write, and Then options Filter and Block, with Read and Filter selected

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Create a conditional rule

  1. Navigate to Data Control Center → Field Controls.
  2. Click Add Conditional Rule.
  3. Fill in the rule settings, then click Add Rule.
For the conditions and values each server supports, see Google Drive and Slack.