diff --git a/crates/idx-mcp/src/params.rs b/crates/idx-mcp/src/params.rs
index 5e3c4a1..88ee860 100644
--- a/crates/idx-mcp/src/params.rs
+++ b/crates/idx-mcp/src/params.rs
@@ -1,6 +1,7 @@
 //! Tool inputs. String enums are validated by idx-core's `FromStr`, so the
 //! accepted values and error messages match the CLI; the schemas list them.
 
+use idx_core::analysis::bandar::TIERS;
 use idx_core::api::types::{Interval, Period};
 use idx_core::broker::types::{BrokerBoard, BrokerInvestor};
 use idx_core::flow::types::FlowSource;
@@ -155,6 +156,7 @@ pub struct BandarParams {
     pub scope: BrokerScope,
     /// Tier behind the headline signal: 1, 3, 5 or 10 brokers per side (default 5).
     #[serde(default)]
+    #[schemars(schema_with = "top_schema")]
     pub top: Option<u8>,
 }
 
@@ -255,3 +257,7 @@ fn board_schema(_: &mut SchemaGenerator) -> Schema {
 fn flow_source_schema(_: &mut SchemaGenerator) -> Schema {
     string_enum(FlowSource::ALL.map(FlowSource::as_str).to_vec())
 }
+
+fn top_schema(_: &mut SchemaGenerator) -> Schema {
+    json_schema!({ "type": "integer", "enum": TIERS })
+}
diff --git a/crates/idx-mcp/tests/golden/tools.json b/crates/idx-mcp/tests/golden/tools.json
index 25cb886..ad343a7 100644
--- a/crates/idx-mcp/tests/golden/tools.json
+++ b/crates/idx-mcp/tests/golden/tools.json
@@ -59,13 +59,13 @@
         "top": {
           "default": null,
           "description": "Tier behind the headline signal: 1, 3, 5 or 10 brokers per side (default 5).",
-          "format": "uint8",
-          "maximum": 255,
-          "minimum": 0,
-          "type": [
-            "integer",
-            "null"
-          ]
+          "enum": [
+            1,
+            3,
+            5,
+            10
+          ],
+          "type": "integer"
         }
       },
       "required": [
diff --git a/web/src/content/docs/mcp/tools.md b/web/src/content/docs/mcp/tools.md
index 7287341..0380cc9 100644
--- a/web/src/content/docs/mcp/tools.md
+++ b/web/src/content/docs/mcp/tools.md
@@ -22,7 +22,7 @@ Bandarmology for one or more IDX tickers from the broker summary: for the top 1,
 | `investor` | `all` / `foreign` / `domestic` | no | Whose trades to count, by investor domicile (default "all"). |
 | `symbols` | array of string | yes | IDX tickers, e.g. ["BBCA", "BBRI"]; the `.JK` suffix is optional. At most 20. |
 | `to` | string | no | Last session of the range, YYYY-MM-DD (default today). |
-| `top` | integer | no | Tier behind the headline signal: 1, 3, 5 or 10 brokers per side (default 5). |
+| `top` | `1` / `3` / `5` / `10` | no | Tier behind the headline signal: 1, 3, 5 or 10 brokers per side (default 5). |
 
 ## `analyze_stock`