diff --git a/.github/workflows/api.yaml b/.github/workflows/api.yaml
index 8e95faa2e2c..388b90ea334 100644
--- a/.github/workflows/api.yaml
+++ b/.github/workflows/api.yaml
@@ -58,6 +58,11 @@ jobs:
         run: |
           echo "GALAXY_CONFIG_OVERRIDE_USE_LAZY_TOOLBOX=true" >> $GITHUB_ENV
           echo "GALAXY_CONFIG_OVERRIDE_TOOL_SOURCE_STORE=database" >> $GITHUB_ENV
+          # Raise instead of silently materialising on any off-surface
+          # LazyTool attribute read, so an accidental whole-toolbox
+          # materialisation regression fails the lazy run loudly rather
+          # than degrading to O(N) tool parses with only a WARN log.
+          echo "LAZY_TOOL_STRICT=1" >> $GITHUB_ENV
       - uses: actions/checkout@v7.0.0
         with:
           path: 'galaxy root'
diff --git a/.github/workflows/integration.yaml b/.github/workflows/integration.yaml
index 6b736b1db33..93c90071e10 100644
--- a/.github/workflows/integration.yaml
+++ b/.github/workflows/integration.yaml
@@ -98,6 +98,11 @@ jobs:
         run: |
           echo "GALAXY_CONFIG_OVERRIDE_USE_LAZY_TOOLBOX=true" >> $GITHUB_ENV
           echo "GALAXY_CONFIG_OVERRIDE_TOOL_SOURCE_STORE=database" >> $GITHUB_ENV
+          # Raise instead of silently materialising on any off-surface
+          # LazyTool attribute read, so an accidental whole-toolbox
+          # materialisation regression fails the lazy run loudly rather
+          # than degrading to O(N) tool parses with only a WARN log.
+          echo "LAZY_TOOL_STRICT=1" >> $GITHUB_ENV
       - name: Prune unused docker image, volumes and containers
         run: docker system prune -a -f
       - name: Clean dotnet folder for space