Default MCP third-party list to level 1

Omit level to return direct third parties; pass level to filter
by hierarchy depth. Documented on the tool and filter field.

Signed-off-by: Sacha Al Himdani <sacha@probo.com>

pkg/server/api/mcp/v1/specification.yaml

@@ -663,7 +663,7 @@ components:
           description: Organization ID
         level:
           type: integer
-          description: Filter by level
+          description: Filter by hierarchy depth (1 = direct third party, 2+ = third party of a third party / indirect). Defaults to 1 when omitted.
         order_by:
           $ref: "#/components/schemas/ThirdPartyOrderBy"
           description: ThirdParty order by
@@ -12606,7 +12606,7 @@ tools:
       $ref: "#/components/schemas/ListOrganizationsOutput"
   - name: listThirdParties
     title: List Third Parties
-    description: List all thirdParties for the organization
+    description: List thirdParties for the organization. By default only direct third parties (level 1) are returned; pass level to filter by hierarchy depth.
     hints:
       readonly: true
       destructive: false