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Disabling Tools

  • reference
Disable specific Couchbase MCP Server tools so they aren’t loaded, discovered, or callable by the LLM.

You can disable specific tools to prevent the server from loading and exposing them to the MCP client. Disabled tools don’t appear in tool discovery, the LLM can’t invoke them, and disabling them cuts noise and unnecessary token consumption.

How It Works

When you specify tools to disable, the server doesn’t load those tools at startup. If you disable a tool, any attempt to call it from the client results in an error response indicating that the tool is unavailable.

Configuration

Environment Variable CLI Argument Description Default

CB_MCP_DISABLED_TOOLS

--disabled-tools

Comma-separated list or file path of tool names to disable

None

Supported Formats

CB_MCP_DISABLED_TOOLS accepts either of these formats.

Comma-Separated List

# Environment variable
CB_MCP_DISABLED_TOOLS="operational_insights_create_index, operational_insights_cancel_async_query"

# Command line
uvx couchbase-mcp-server operational-insights --disabled-tools "operational_insights_create_index, operational_insights_cancel_async_query"

File Path (One Tool Per Line)

# Environment variable
CB_MCP_DISABLED_TOOLS=/path/to/disabled_tools.txt

# Command line
uvx couchbase-mcp-server operational-insights --disabled-tools /path/to/disabled_tools.txt

File format example (disabled_tools.txt):

# Index and async query management
operational_insights_create_index
operational_insights_cancel_async_query

The server treats lines starting with # as comments and ignores them.

MCP Client Configuration Examples

Using comma-separated list:

{
  "mcpServers": {
    "couchbase-oi": {
      "command": "uvx",
      "args": ["couchbase-mcp-server", "operational-insights"],
      "env": {
        "CB_OPERATIONAL_INSIGHTS_CONNECTION_STRING": "https://your-oi-endpoint",
        "CB_OPERATIONAL_INSIGHTS_USERNAME": "username",
        "CB_OPERATIONAL_INSIGHTS_PASSWORD": "password",
        "CB_MCP_DISABLED_TOOLS": "operational_insights_create_index,operational_insights_cancel_async_query"
      }
    }
  }
}

Using file path (recommended for many tools):

{
  "mcpServers": {
    "couchbase-oi": {
      "command": "uvx",
      "args": ["couchbase-mcp-server", "operational-insights"],
      "env": {
        "CB_OPERATIONAL_INSIGHTS_CONNECTION_STRING": "https://your-oi-endpoint",
        "CB_OPERATIONAL_INSIGHTS_USERNAME": "username",
        "CB_OPERATIONAL_INSIGHTS_PASSWORD": "password",
        "CB_MCP_DISABLED_TOOLS": "/path/to/disabled_tools.txt"
      }
    }
  }
}

Important Security Note

Disabling tools alone doesn’t prevent certain operations from happening.

The underlying database user’s RBAC (Role-Based Access Control) permissions are the authoritative security control. For example, even if you disable operational_insights_create_index, you can still attempt index and structural changes via the operational_insights_run_query_sync/operational_insights_run_query_async tools using SQL++ DDL statements unless:

  • CB_MCP_READ_ONLY_MODE is set to true (default), which runs SQL++ queries with the server-side readonly option,

OR

  • The database user lacks the necessary RBAC permissions

Best Practice

Always configure appropriate RBAC permissions on your Couchbase user credentials as the primary security measure. See RBAC for Couchbase Server. Use tool disabling as an additional layer to guide LLM behavior and reduce the attack surface, not as the sole security control.