Tooling API vs Metadata API (Simple Explanation) 

Tooling API 

• Designed for developer tools (VSCode, Developer Console, etc.)
• Can access runtime information (e.g., ApexClass, LightningComponentBundle)
• Faster and easier for use in Apex
• Commonly used to query: Apex classes, LWC, Triggers, etc.

Metadata API

• Used for deployment and configuration.
• Accesses complete metadata (e.g., Object schema, Layouts, Flows)
• Needs Session ID with OAuth, not always available inside Flows or Agents.
• Cannot be queried easily using Apex in real-time – usually used via external tools or HTTP callouts.

Why You’re Getting Zero in Flow/Agent 

• When using Metadata API in Apex, it usually requires callouts with valid Session ID.
• In Flow/Agent, that Session ID is often null or restricted due to platform security.
• Tooling API inside Apex may not return results when invoked from Flow or Bot Agent due to permission scoping.
• Anonymous Apex (Dev Console) runs with full user-level permissions, which is why it works there.

Recommended: Use Tooling API with Apex (Simple Count Logic) 

Here’s working Apex code to count: 

• Lightning Web Components
• Flows
• Process Builders
• Custom Objects (Excluding Managed Packages)

 public class OrgMetadataCounter {    public class MetadataCountResult {        public Integer lwcCount;        public Integer flowCount;        public Integer pbCount;        public Integer customObjectCount;    }    public static MetadataCountResult getComponentCounts() {        MetadataCountResult result = new MetadataCountResult();        // LWC Count (Tooling API)        result.lwcCount = [SELECT COUNT() FROM LightningComponentBundle WHERE NamespacePrefix = null AND DeveloperName != null];        // Flow Count (Metadata API via Tooling)        result.flowCount = [SELECT COUNT() FROM FlowDefinitionView WHERE ProcessType = 'Flow'];        // Process Builder Count        result.pbCount = [SELECT COUNT() FROM FlowDefinitionView WHERE ProcessType = 'Workflow'];        // Custom Object Count (Standard + Custom, Excluding Managed Packages)        result.customObjectCount = [SELECT COUNT() FROM CustomObject WHERE NamespacePrefix = null];        return result;    }}