Sanitize MCP errors to avoid leaking internal details

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

e2e/internal/testutil/mcp.go

@@ -204,6 +204,20 @@ func (mc *MCPClient) CallTool(toolName string, args map[string]any) *MCPToolResu
 	return &toolResult
 }
 
+// CallToolExpectToolError invokes an MCP tool and expects a tool-level error
+// (isError: true in the result). It returns the error text content.
+func (mc *MCPClient) CallToolExpectToolError(toolName string, args map[string]any) string {
+	tr := mc.CallTool(toolName, args)
+	require.True(mc.t, tr.IsError, "expected tool %s to return isError", toolName)
+	require.NotEmpty(mc.t, tr.Content, "tool %s returned no content", toolName)
+
+	var text string
+	err := json.Unmarshal(tr.Content[0].Text, &text)
+	require.NoError(mc.t, err, "cannot unmarshal error text for %s", toolName)
+
+	return text
+}
+
 // CallToolInto invokes an MCP tool and unmarshals the first text content into dest.
 func (mc *MCPClient) CallToolInto(toolName string, args map[string]any, dest any) {
 	tr := mc.CallTool(toolName, args)

e2e/mcp/asset_test.go

@@ -92,4 +92,27 @@ func TestMCP_Asset_CRUD(t *testing.T) {
 		"id": addResult.Asset.ID,
 	}, &deleteResult)
 	assert.Equal(t, addResult.Asset.ID, deleteResult.DeletedAssetID)
+
+	// Get deleted asset returns sanitized not-found error
+	msg := mc.CallToolExpectToolError("getAsset", map[string]any{
+		"id": addResult.Asset.ID,
+	})
+	assert.Equal(t, "resource not found", msg)
+}
+
+func TestMCP_Asset_PermissionDenied(t *testing.T) {
+	t.Parallel()
+	owner := testutil.NewClient(t, testutil.RoleOwner)
+	orgID := owner.GetOrganizationID().String()
+	viewer := testutil.NewClientInOrg(t, testutil.RoleViewer, owner)
+	viewerMC := testutil.NewMCPClient(t, viewer)
+
+	msg := viewerMC.CallToolExpectToolError("addAsset", map[string]any{
+		"organizationId":  orgID,
+		"name":            factory.SafeName("Asset"),
+		"amount":          1,
+		"assetType":       "VIRTUAL",
+		"dataTypesStored": "PII",
+	})
+	assert.Contains(t, msg, "permission denied")
 }

e2e/mcp/risk_test.go

@@ -86,4 +86,24 @@ func TestMCP_Risk_CRUD(t *testing.T) {
 		"id": addResult.Risk.ID,
 	}, &deleteResult)
 	assert.Equal(t, addResult.Risk.ID, deleteResult.DeletedRiskID)
+
+	// Get deleted risk returns sanitized not-found error
+	msg := mc.CallToolExpectToolError("getRisk", map[string]any{
+		"id": addResult.Risk.ID,
+	})
+	assert.Equal(t, "resource not found", msg)
+}
+
+func TestMCP_Risk_PermissionDenied(t *testing.T) {
+	t.Parallel()
+	owner := testutil.NewClient(t, testutil.RoleOwner)
+	orgID := owner.GetOrganizationID().String()
+	viewer := testutil.NewClientInOrg(t, testutil.RoleViewer, owner)
+	viewerMC := testutil.NewMCPClient(t, viewer)
+
+	msg := viewerMC.CallToolExpectToolError("addRisk", map[string]any{
+		"organizationId": orgID,
+		"name":           factory.SafeName("Risk"),
+	})
+	assert.Contains(t, msg, "permission denied")
 }

e2e/mcp/vendor_test.go

@@ -76,4 +76,42 @@ func TestMCP_Vendor_CRUD(t *testing.T) {
 		"id": addResult.Vendor.ID,
 	}, &deleteResult)
 	assert.Equal(t, addResult.Vendor.ID, deleteResult.DeletedVendorID)
+
+	// Update deleted vendor returns sanitized not-found error
+	msg := mc.CallToolExpectToolError("updateVendor", map[string]any{
+		"id":   addResult.Vendor.ID,
+		"name": "Should Fail",
+	})
+	assert.Equal(t, "resource not found", msg)
+}
+
+func TestMCP_Vendor_ValidationError(t *testing.T) {
+	t.Parallel()
+	owner := testutil.NewClient(t, testutil.RoleOwner)
+	mc := testutil.NewMCPClient(t, owner)
+	orgID := owner.GetOrganizationID().String()
+
+	msg := mc.CallToolExpectToolError("addVendor", map[string]any{
+		"organizationId": orgID,
+		"name":           "",
+	})
+	assert.Contains(t, msg, "name")
+	assert.NotContains(t, msg, "pq:")
+	assert.NotContains(t, msg, "sql:")
+}
+
+func TestMCP_Vendor_PermissionDenied(t *testing.T) {
+	t.Parallel()
+	owner := testutil.NewClient(t, testutil.RoleOwner)
+	orgID := owner.GetOrganizationID().String()
+	viewer := testutil.NewClientInOrg(t, testutil.RoleViewer, owner)
+	viewerMC := testutil.NewMCPClient(t, viewer)
+
+	msg := viewerMC.CallToolExpectToolError("addVendor", map[string]any{
+		"organizationId": orgID,
+		"name":           factory.SafeName("Vendor"),
+	})
+	assert.Contains(t, msg, "permission denied")
+	assert.NotContains(t, msg, "pq:")
+	assert.NotContains(t, msg, "sql:")
 }