diff --git a/ErsatzTV.Mcp/ToolCatalog.cs b/ErsatzTV.Mcp/ToolCatalog.cs
index 33918184c..6e5ad0ad1 100644
--- a/ErsatzTV.Mcp/ToolCatalog.cs
+++ b/ErsatzTV.Mcp/ToolCatalog.cs
@@ -50,7 +50,8 @@ public static class ToolCatalog
             [
                 Bool(
                     "showFiller",
-                    "Include filler items (pre/mid/post-roll, tail) in the result; default false returns only non-filler items.",
+                    "Include items whose filler kind is not None (pre/mid/post-roll, tail, fallback, guide-mode, deco); "
+                    + "default false returns only non-filler items.",
                     arg: In.Query),
                 .. Page()
             ]),
diff --git a/docs/decisions/records/mcp/tool-schema-openapi-parity.md b/docs/decisions/records/mcp/tool-schema-openapi-parity.md
index 9ec8234f8..215c8b4bb 100644
--- a/docs/decisions/records/mcp/tool-schema-openapi-parity.md
+++ b/docs/decisions/records/mcp/tool-schema-openapi-parity.md
@@ -64,6 +64,14 @@ the same shape with paging). That test **accumulates** its mismatches and assert
 reports the whole drift set — failing on the first would invite fixing one tool at a time, which is
 how the twin in this very issue stayed hidden.
 
+It also **composes with** the older `Every_Query_Parameter_Should_Be_A_Declared_Property`, and the pair
+is the clearest illustration in this repo of why "a test that filters on the property it asserts cannot
+see what is missing" is a rule. That older test filters `Where(t => t.QueryParameters is { Count: > 0 })`
+— so a tool that lost its query parameters entirely escaped it, which is exactly how `list_playouts` and
+`get_playout_items` hid. The new test has no filter and reports them as *unreachable*; the old one then
+checks that a routed parameter is also a declared argument. Neither subsumes the other, and the inner
+duplicate of the old check was deliberately removed from the new test rather than kept as a second copy.
+
 **Scope, stated so it is not mistaken for more.** Request bodies are compared for POST/PUT/PATCH only.
 DELETE is uncovered because `ErsatzTvApiClient` builds a body for POST/PUT/PATCH only, so a body
 argument on a DELETE tool would be silently dropped; no tool has one today. Header arguments (`ifMatch`)