diff --git a/ddtrace/_trace/span.py b/ddtrace/_trace/span.py
index 6180f70db7d..fb15ca2a4b6 100644
--- a/ddtrace/_trace/span.py
+++ b/ddtrace/_trace/span.py
@@ -240,13 +240,20 @@ def _set_sampling_decision_maker(
         self.context._meta[SAMPLING_DECISION_TRACE_TAG_KEY] = value
         return value
 
-    def set_tag(self, key: str, value: Optional[str] = None) -> None:
-        """Set a tag key/value pair on the span."""
+    def set_tag(self, key: str, value: Any = None) -> None:
+        """Set a tag key/value pair on the span.
+
+        Boolean and bytes values are stored as their string representation. Finite floats
+        and integers within the signed 64-bit range are stored as metrics (see
+        ``set_metric``); integers outside that range fall back to their string
+        representation, and NaN or infinite floats are discarded. ``http.status_code`` is
+        always stored as a string.
+        """
         # Explicitly try to convert expected integers to `int`
         # DEV: Some integrations parse these values from strings, but don't call `int(value)` themselves
         if key == net.TARGET_PORT:
             try:
-                value = int(value)  # type: ignore
+                value = int(value)
             except (ValueError, TypeError):
                 pass
 
@@ -261,14 +268,14 @@ def set_tag(self, key: str, value: Optional[str] = None) -> None:
         elif key == SERVICE_VERSION_KEY:
             # Also set the `version` tag to the same value
             # DEV: Note that we do no return, we want to set both
-            self._set_attribute(VERSION_KEY, value)  # type: ignore[arg-type]
+            self._set_attribute(VERSION_KEY, value)
         elif key == _SPAN_MEASURED_KEY:
             # Set `_dd.measured` tag as a metric
             # DEV: `set_metric` will ensure it is an integer 0 or 1
             if value is None:
-                value = 1  # type: ignore
+                value = 1
 
-            self.set_metric(key, value)  # type: ignore[arg-type]  # ast-grep-ignore: span-set-metric
+            self.set_metric(key, value)  # ast-grep-ignore: span-set-metric
             return
 
         if isinstance(key, bytes):
@@ -278,7 +285,7 @@ def set_tag(self, key: str, value: Optional[str] = None) -> None:
             value = str(value)
 
         try:
-            self._set_attribute(key, value)  # type: ignore[arg-type]
+            self._set_attribute(key, value)
         except Exception:
             log.warning("error setting tag %s, ignoring it", key, exc_info=True)
 
diff --git a/releasenotes/notes/widen-set-tag-value-typing-40a41e0a8804ec18.yaml b/releasenotes/notes/widen-set-tag-value-typing-40a41e0a8804ec18.yaml
new file mode 100644
index 00000000000..c64bd12b434
--- /dev/null
+++ b/releasenotes/notes/widen-set-tag-value-typing-40a41e0a8804ec18.yaml
@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    tracing: This fix resolves an issue where type checkers rejected valid application code passing
+    non-string values to ``Span.set_tag`` (for example ``span.set_tag("custom.tag", True)``). The
+    ``value`` parameter was annotated as ``Optional[str]``, but the implementation accepts the
+    historic domain: booleans and bytes are stringified into tags, and numeric values are stored
+    as metrics.