Sub catalogs enable sharing private catalogs with other organizations. This is useful when distributing internal MCP tools to partners, customers, or other teams within a company that operate as separate Gram organizations.

The peered organization model

Gram uses a super/sub organization model to manage cross-organization catalog sharing:

• The super organization owns the catalog and controls who can access it
• A sub organization is granted access to specific catalogs from the super organization

Super Organization
├── Catalog: "customer-success"
├── Catalog: "data-platform"
│
├── Peer: Sub Org A  →  granted: "customer-success"
└── Peer: Sub Org B  →  granted: "customer-success", "data-platform"

When a sub organization is granted access to a catalog, the catalog MCP servers appear alongside its own registries. From the sub organization’s perspective, these shared catalogs are sub catalogs — read-only collections of tools provided by the parent organization.

Setting up sub catalogs

Step 1: Create a peer relationship

Before sharing catalogs, establish a peer relationship with the target organization. In the Gram dashboard:

• Navigate to Settings
• Under the Peers section, click Add Peer
• Enter the sub organization ID to create the relationship

Step 2: Grant catalog access

Once a peer relationship exists, grant the sub organization access to specific catalogs:

• Navigate to Catalogs and select the catalog to share
• Under Access, click Grant Access
• Select the peered organization from the list

The sub organization will now see this catalog in its registry list and can browse the MCP servers.

Step 3: Sub organization connects to catalog servers

From the sub organization dashboard, the granted catalog appears in the Catalogs view. From there:

• Browse the available MCP servers in the catalog
• View server details including available tools and descriptions
• Connect to servers using the standard MCP client configuration

Managing access

Revoking access

To remove a sub organization’s access to a catalog:

• Navigate to the catalog in the dashboard
• Under Access, find the organization and click Revoke

The sub organization will immediately lose access to the catalog MCP servers.

Removing a peer relationship

Deleting a peer relationship automatically revokes all catalog grants for that sub organization. Navigate to Settings > Peers and remove the peer.

How sub catalog resolution works

When a sub organization lists available registries, Gram combines:

• Own registries — any external MCP registries configured by the organization
• Own catalogs — any internal catalogs published by the organization
• Granted sub catalogs — catalogs shared by super organizations through peering

This merged view means sub organizations can seamlessly use tools from their own projects alongside tools shared by partner organizations.

Next steps

• Learn how to create catalogs to organize toolsets
• Read about controlling server visibility for fine-grained access control