diff --git a/internal/mcp/bridge_tool.go b/internal/mcp/bridge_tool.go
index 51c4de78..93674a47 100644
--- a/internal/mcp/bridge_tool.go
+++ b/internal/mcp/bridge_tool.go
@@ -370,12 +370,18 @@ func (t *BridgeTool) stripEmptyOptionalArgs(args map[string]any) map[string]any
 		}
 		if s, ok := v.(string); ok {
 			// Strip known placeholder values (e.g. "optional", "null", "http://example.com").
+			// Logged: dropping an argument silently changes query semantics (a filtered
+			// call becomes unfiltered) and is otherwise invisible in traces.
 			if isPlaceholderValue(s) {
+				slog.Warn("mcp.tool.args.stripped",
+					"tool", t.registeredName, "arg", k, "value", s, "reason", "placeholder")
 				continue
 			}
 			// Type-aware empty string: keep for string-typed params (user may want empty),
 			// strip for non-string params (empty string is never valid for number/boolean/UUID).
 			if s == "" && t.propertyType(k) != "string" {
+				slog.Warn("mcp.tool.args.stripped",
+					"tool", t.registeredName, "arg", k, "reason", "empty_string_non_string_param")
 				continue
 			}
 		}
@@ -441,17 +447,40 @@ func detectLogicalErrorPayload(text string) (string, bool) {
 
 // isAllCapsPlaceholder detects LLM-generated all-caps placeholder strings
 // like "SHOULD_NOT_BE_HERE", "DO_NOT_SEND", "NOT_APPLICABLE", "PLACEHOLDER".
+//
+// NOTE: being all-caps is NOT sufficient. Real business identifiers are commonly
+// all-caps: bank codes (BKASH, NAGAD, ROCKET), currency codes (BDT, VND, USD),
+// country codes, ticker symbols, enum values (SUCCESS, PENDING). Silently dropping
+// those turns a filtered query into an unfiltered one — the MCP server still returns
+// 200 with the full result set, so neither the model nor the operator notices, and
+// the model then reports a wrong number with full confidence.
+//
+// Only treat a value as a placeholder when it is multi-word (contains "_") or matches
+// a known single-word placeholder.
 func isAllCapsPlaceholder(s string) bool {
 	trimmed := strings.TrimSpace(s)
 	if len(trimmed) < 3 {
 		return false
 	}
+	hasUnderscore := false
 	for _, r := range trimmed {
-		if r != '_' && (r < 'A' || r > 'Z') {
+		if r == '_' {
+			hasUnderscore = true
+			continue
+		}
+		if r < 'A' || r > 'Z' {
 			return false
 		}
 	}
-	return true
+	if hasUnderscore {
+		return true
+	}
+	switch trimmed {
+	case "PLACEHOLDER", "TODO", "TBD", "XXX", "NONE", "NULL", "UNKNOWN",
+		"VALUE", "STRING", "EXAMPLE", "CHANGEME", "REPLACE", "OMIT", "SKIP":
+		return true
+	}
+	return false
 }
 
 // wrapMCPContent wraps MCP tool results as external/untrusted content.
diff --git a/internal/mcp/bridge_tool_test.go b/internal/mcp/bridge_tool_test.go
index 55de8302..ea92b7d6 100644
--- a/internal/mcp/bridge_tool_test.go
+++ b/internal/mcp/bridge_tool_test.go
@@ -483,3 +483,66 @@ func TestEnsureMCPPrefix(t *testing.T) {
 		})
 	}
 }
+
+// TestIsAllCapsPlaceholder_KeepsBusinessCodes guards a production incident:
+// all-caps business identifiers (bank codes, currency codes, enum values) were
+// classified as LLM placeholders and silently dropped from tool arguments, so a
+// filtered query silently became an unfiltered one and the model reported totals
+// for the whole dataset as if they were the filtered result.
+func TestIsAllCapsPlaceholder_KeepsBusinessCodes(t *testing.T) {
+	keep := []string{
+		"BKASH", "NAGAD", "ROCKET", "ROCKETC", // bank codes
+		"BDT", "VND", "USD", "PKR", "MMK", // currency codes
+		"SUCCESS", "PENDING", "ALL", // enum values
+		"VCB", "SPACEPROXY",
+	}
+	for _, s := range keep {
+		if isAllCapsPlaceholder(s) {
+			t.Errorf("business identifier %q must NOT be treated as a placeholder", s)
+		}
+	}
+
+	drop := []string{
+		"SHOULD_NOT_BE_HERE", "DO_NOT_SEND", "NOT_APPLICABLE", // multi-word
+		"PLACEHOLDER", "TODO", "TBD", "XXX", "CHANGEME", // known single-word
+	}
+	for _, s := range drop {
+		if !isAllCapsPlaceholder(s) {
+			t.Errorf("placeholder %q must be detected", s)
+		}
+	}
+}
+
+// TestStripEmptyOptionalArgs_KeepsAllCapsBusinessCode is the end-to-end guard for
+// the same incident, at the layer that actually mutates the outbound arguments.
+func TestStripEmptyOptionalArgs_KeepsAllCapsBusinessCode(t *testing.T) {
+	bt := &BridgeTool{
+		requiredSet: map[string]bool{"merchant_id": true},
+		inputSchema: map[string]any{
+			"type": "object",
+			"properties": map[string]any{
+				"merchant_id": map[string]any{"type": "string"},
+				"bank_code":   map[string]any{"type": "string"},
+				"currency":    map[string]any{"type": "string"},
+				"note":        map[string]any{"type": "string"},
+			},
+		},
+	}
+
+	cleaned := bt.stripEmptyOptionalArgs(map[string]any{
+		"merchant_id": "CPS_C1",
+		"bank_code":   "BKASH",              // optional all-caps business code → keep
+		"currency":    "BDT",                // optional all-caps business code → keep
+		"note":        "SHOULD_NOT_BE_HERE", // real placeholder → strip
+	})
+
+	if cleaned["bank_code"] != "BKASH" {
+		t.Errorf("bank_code must survive, got %v", cleaned["bank_code"])
+	}
+	if cleaned["currency"] != "BDT" {
+		t.Errorf("currency must survive, got %v", cleaned["currency"])
+	}
+	if _, ok := cleaned["note"]; ok {
+		t.Error("multi-word all-caps placeholder should still be stripped")
+	}
+}