diff --git a/.changeset/expose-series-limit-external-api.md b/.changeset/expose-series-limit-external-api.md
new file mode 100644
index 0000000000..7b15cb1c94
--- /dev/null
+++ b/.changeset/expose-series-limit-external-api.md
@@ -0,0 +1,5 @@
+---
+'@hyperdx/api': patch
+---
+
+fix: Expose `seriesLimit` via external API and MCP
\ No newline at end of file
diff --git a/packages/api/openapi.json b/packages/api/openapi.json
index 4c076f92fa..c2fbbb9aee 100644
--- a/packages/api/openapi.json
+++ b/packages/api/openapi.json
@@ -1642,6 +1642,12 @@
             "type": "boolean",
             "description": "Overlay the equivalent previous time period for comparison.",
             "default": false
+          },
+          "seriesLimit": {
+            "type": "integer",
+            "minimum": 1,
+            "description": "Maximum number of series rendered (top-N by value). Omit for no limit.",
+            "example": 5
           }
         }
       },
@@ -1700,6 +1706,12 @@
           "numberFormat": {
             "$ref": "#/components/schemas/NumberFormat",
             "description": "Number formatting options for displayed values."
+          },
+          "seriesLimit": {
+            "type": "integer",
+            "minimum": 1,
+            "description": "Maximum number of series rendered (top-N by value). Omit for no limit.",
+            "example": 5
           }
         }
       },
diff --git a/packages/api/src/mcp/__tests__/dashboards/patchDashboard.int.test.ts b/packages/api/src/mcp/__tests__/dashboards/patchDashboard.int.test.ts
index f318568c07..f8f9d8eeef 100644
--- a/packages/api/src/mcp/__tests__/dashboards/patchDashboard.int.test.ts
+++ b/packages/api/src/mcp/__tests__/dashboards/patchDashboard.int.test.ts
@@ -705,6 +705,61 @@ describe('MCP Dashboard Tools - clickstack_patch_dashboard', () => {
     });
   });
 
+  it('should round-trip seriesLimit: patch then get_dashboard_tile', async () => {
+    const sourceId = ctx.traceSource._id.toString();
+    const createResult = await callTool(
+      ctx.client!,
+      'clickstack_save_dashboard',
+      {
+        name: 'Series Limit Patch Test',
+        tiles: [
+          {
+            name: 'Original',
+            config: {
+              displayType: 'line',
+              sourceId,
+              select: [{ aggFn: 'count' }],
+              groupBy: 'SpanName',
+              seriesLimit: 5,
+            },
+          },
+        ],
+      },
+    );
+    const created = JSON.parse(getFirstText(createResult));
+    expect(created.tiles[0].config.seriesLimit).toBe(5);
+    const tileId = created.tiles[0].id;
+
+    await callTool(ctx.client!, 'clickstack_patch_dashboard', {
+      dashboardId: created.id,
+      tileId,
+      tile: {
+        name: 'Patched',
+        config: {
+          displayType: 'stacked_bar',
+          sourceId,
+          select: [{ aggFn: 'count' }],
+          groupBy: 'SpanName',
+          seriesLimit: 3,
+        },
+      },
+    });
+
+    const getResult = await callTool(
+      ctx.client!,
+      'clickstack_get_dashboard_tile',
+      {
+        dashboardId: created.id,
+        tileId,
+      },
+    );
+
+    expect(getResult.isError).toBeFalsy();
+    const tile = JSON.parse(getFirstText(getResult));
+    expect(tile.config.displayType).toBe('stacked_bar');
+    expect(tile.config.seriesLimit).toBe(3);
+  });
+
   describe('raw SQL macro warnings', () => {
     // Patching a tile to a macro-less raw SQL config succeeds (non-blocking)
     // but surfaces an advisory `warnings` array on the response.
diff --git a/packages/api/src/mcp/__tests__/dashboards/saveDashboard.int.test.ts b/packages/api/src/mcp/__tests__/dashboards/saveDashboard.int.test.ts
index 497696d202..c4240711a8 100644
--- a/packages/api/src/mcp/__tests__/dashboards/saveDashboard.int.test.ts
+++ b/packages/api/src/mcp/__tests__/dashboards/saveDashboard.int.test.ts
@@ -942,15 +942,19 @@ describe('MCP Dashboard Tools - clickstack_save_dashboard', () => {
         displayType: 'line' as const,
         sourceId,
         select: [{ aggFn: 'count' as const, alias: 'Requests' }],
+        groupBy: 'SpanName',
         numberFormat,
         compareToPreviousPeriod: true,
         fitYAxisToData: true,
+        seriesLimit: 5,
       };
       const barConfig = {
         displayType: 'stacked_bar' as const,
         sourceId,
         select: [{ aggFn: 'count' as const, alias: 'Requests' }],
+        groupBy: 'SpanName',
         numberFormat,
+        seriesLimit: 3,
       };
       const tableConfig = {
         displayType: 'table' as const,
diff --git a/packages/api/src/mcp/tools/dashboards/schemas.ts b/packages/api/src/mcp/tools/dashboards/schemas.ts
index e0e92e830f..75b85d89d9 100644
--- a/packages/api/src/mcp/tools/dashboards/schemas.ts
+++ b/packages/api/src/mcp/tools/dashboards/schemas.ts
@@ -47,6 +47,14 @@ const tileLevelNumberFormatDescription =
   'Most useful: { output: "duration", factor: 0.000000001 } to auto-format nanosecond durations, ' +
   'or { output: "number", mantissa: 2, thousandSeparated: true } for clean counts.';
 
+const timeChartSeriesLimitDescription =
+  'Maximum number of series to fetch (the "Series Limit" display setting). ' +
+  'Keeps the top-N groups by aggregated value over the queried range and ' +
+  'drops the rest. Requires `groupBy`; ignored on a chart without one. ' +
+  'Omit to fetch every series.';
+
+const seriesLimitSchema = z.number().int().positive().optional();
+
 const numberTileColorDescription =
   'Static color for the displayed number, as a palette token such as ' +
   '"chart-blue", "chart-green", or "chart-success" (see the enum for the ' +
@@ -534,6 +542,7 @@ const mcpLineTileSchema = mcpTileLayoutSchema.extend({
       .describe(
         'Scale the y-axis to the data range instead of starting at zero.',
       ),
+    seriesLimit: seriesLimitSchema.describe(timeChartSeriesLimitDescription),
   }),
 });
 
@@ -551,6 +560,7 @@ const mcpBarTileSchema = mcpTileLayoutSchema.extend({
     numberFormat: mcpNumberFormatSchema
       .optional()
       .describe(tileLevelNumberFormatDescription),
+    seriesLimit: seriesLimitSchema.describe(timeChartSeriesLimitDescription),
   }),
 });
 
diff --git a/packages/api/src/routers/external-api/__tests__/dashboards.int.test.ts b/packages/api/src/routers/external-api/__tests__/dashboards.int.test.ts
index d1b7323eb4..e860f3aba5 100644
--- a/packages/api/src/routers/external-api/__tests__/dashboards.int.test.ts
+++ b/packages/api/src/routers/external-api/__tests__/dashboards.int.test.ts
@@ -2593,6 +2593,109 @@ describe('External API v2 Dashboards - new format', () => {
       );
     });
 
+    it('persists seriesLimit on line and stacked_bar tiles through create and get', async () => {
+      // Regression test for HDX-4988: seriesLimit was silently dropped on
+      // line/stacked_bar tiles. Exercises both the input-schema acceptance
+      // and the internal<->external conversion round-trip.
+      const lineChart: ExternalDashboardTile = {
+        name: 'Line with series limit',
+        x: 0,
+        y: 0,
+        w: 6,
+        h: 3,
+        config: {
+          displayType: 'line',
+          sourceId: traceSource._id.toString(),
+          select: [
+            {
+              aggFn: 'count',
+              alias: 'Count',
+              where: '',
+              whereLanguage: 'sql',
+            },
+          ],
+          groupBy: 'ServiceName',
+          seriesLimit: 20,
+        },
+      };
+
+      const stackedBarChart: ExternalDashboardTile = {
+        name: 'Stacked bar with series limit',
+        x: 6,
+        y: 0,
+        w: 6,
+        h: 3,
+        config: {
+          displayType: 'stacked_bar',
+          sourceId: traceSource._id.toString(),
+          select: [
+            {
+              aggFn: 'count',
+              alias: 'Count',
+              where: '',
+              whereLanguage: 'sql',
+            },
+          ],
+          groupBy: 'ServiceName',
+          seriesLimit: 7,
+        },
+      };
+
+      // Act: create the dashboard
+      const createResponse = await authRequest('post', BASE_URL)
+        .send({
+          name: 'Dashboard with series limits',
+          tiles: [lineChart, stackedBarChart],
+        })
+        .expect(200);
+
+      // Assert: create response echoes the seriesLimit back
+      expect(createResponse.body.data.tiles[0].config.seriesLimit).toBe(20);
+      expect(createResponse.body.data.tiles[1].config.seriesLimit).toBe(7);
+
+      // Assert: the seriesLimit survives a round-trip through persistence (GET)
+      const { id } = createResponse.body.data;
+      const getResponse = await authRequest('get', `${BASE_URL}/${id}`).expect(
+        200,
+      );
+      expect(getResponse.body.data.tiles[0].config.seriesLimit).toBe(20);
+      expect(getResponse.body.data.tiles[1].config.seriesLimit).toBe(7);
+    });
+
+    it('omits seriesLimit on line/stacked_bar tiles when it is not provided', async () => {
+      const lineChart: ExternalDashboardTile = {
+        name: 'Line without series limit',
+        x: 0,
+        y: 0,
+        w: 6,
+        h: 3,
+        config: {
+          displayType: 'line',
+          sourceId: traceSource._id.toString(),
+          select: [
+            {
+              aggFn: 'count',
+              alias: 'Count',
+              where: '',
+              whereLanguage: 'sql',
+            },
+          ],
+          groupBy: 'ServiceName',
+        },
+      };
+
+      const response = await authRequest('post', BASE_URL)
+        .send({
+          name: 'Dashboard without series limit',
+          tiles: [lineChart],
+        })
+        .expect(200);
+
+      expect(response.body.data.tiles[0].config).not.toHaveProperty(
+        'seriesLimit',
+      );
+    });
+
     it('omits orderBy on pie/bar tiles when it is not provided', async () => {
       const pieChart: ExternalDashboardTile = {
         name: 'Pie without order',
@@ -3643,6 +3746,73 @@ describe('External API v2 Dashboards - new format', () => {
       );
     });
 
+    it('persists seriesLimit on line and stacked_bar tiles through update and get', async () => {
+      // Regression test for HDX-4988: the save path must not drop
+      // seriesLimit on line/stacked_bar tiles.
+      const dashboard = await createTestDashboard();
+      const lineChart: ExternalDashboardTileWithId = {
+        id: new ObjectId().toString(),
+        name: 'Line with series limit',
+        x: 0,
+        y: 0,
+        w: 6,
+        h: 3,
+        config: {
+          displayType: 'line',
+          sourceId: traceSource._id.toString(),
+          select: [
+            {
+              aggFn: 'count',
+              alias: 'Count',
+              where: '',
+              whereLanguage: 'sql',
+            },
+          ],
+          groupBy: 'ServiceName',
+          seriesLimit: 15,
+        },
+      };
+      const stackedBarChart: ExternalDashboardTileWithId = {
+        id: new ObjectId().toString(),
+        name: 'Stacked bar with series limit',
+        x: 6,
+        y: 0,
+        w: 6,
+        h: 3,
+        config: {
+          displayType: 'stacked_bar',
+          sourceId: traceSource._id.toString(),
+          select: [
+            {
+              aggFn: 'count',
+              alias: 'Count',
+              where: '',
+              whereLanguage: 'sql',
+            },
+          ],
+          groupBy: 'ServiceName',
+          seriesLimit: 3,
+        },
+      };
+
+      const response = await authRequest('put', `${BASE_URL}/${dashboard._id}`)
+        .send({
+          name: 'Dashboard with series limits',
+          tiles: [lineChart, stackedBarChart],
+        })
+        .expect(200);
+
+      expect(response.body.data.tiles[0].config.seriesLimit).toBe(15);
+      expect(response.body.data.tiles[1].config.seriesLimit).toBe(3);
+
+      const getResponse = await authRequest(
+        'get',
+        `${BASE_URL}/${dashboard._id}`,
+      ).expect(200);
+      expect(getResponse.body.data.tiles[0].config.seriesLimit).toBe(15);
+      expect(getResponse.body.data.tiles[1].config.seriesLimit).toBe(3);
+    });
+
     it('should update dashboard filters when provided', async () => {
       const dashboard = await createTestDashboard();
       const filterId1 = new ObjectId().toString();
diff --git a/packages/api/src/routers/external-api/v2/dashboards.ts b/packages/api/src/routers/external-api/v2/dashboards.ts
index 3bb6749daf..f3d92bed45 100644
--- a/packages/api/src/routers/external-api/v2/dashboards.ts
+++ b/packages/api/src/routers/external-api/v2/dashboards.ts
@@ -629,6 +629,11 @@ const EXTERNAL_DASHBOARD_PROJECTION = {
  *           type: boolean
  *           description: Overlay the equivalent previous time period for comparison.
  *           default: false
+ *         seriesLimit:
+ *           type: integer
+ *           minimum: 1
+ *           description: Maximum number of series rendered (top-N by value). Omit for no limit.
+ *           example: 5
  *
  *     BarBuilderChartConfig:
  *       type: object
@@ -676,6 +681,11 @@ const EXTERNAL_DASHBOARD_PROJECTION = {
  *         numberFormat:
  *           $ref: '#/components/schemas/NumberFormat'
  *           description: Number formatting options for displayed values.
+ *         seriesLimit:
+ *           type: integer
+ *           minimum: 1
+ *           description: Maximum number of series rendered (top-N by value). Omit for no limit.
+ *           example: 5
  *
  *     TableBuilderChartConfig:
  *       type: object
diff --git a/packages/api/src/routers/external-api/v2/utils/dashboards.ts b/packages/api/src/routers/external-api/v2/utils/dashboards.ts
index 638efbcb1b..42522b0abe 100644
--- a/packages/api/src/routers/external-api/v2/utils/dashboards.ts
+++ b/packages/api/src/routers/external-api/v2/utils/dashboards.ts
@@ -15,7 +15,6 @@ import {
 import {
   AggregateFunctionSchema,
   BuilderSavedChartConfig,
-  ChartPaletteToken,
   ColorCondition,
   DASHBOARD_MAX_CONTAINERS,
   DashboardContainer,
@@ -300,6 +299,7 @@ const convertToExternalTileChartConfig = (
           : [DEFAULT_SELECT_ITEM],
         compareToPreviousPeriod: config.compareToPreviousPeriod,
         numberFormat: config.numberFormat,
+        seriesLimit: config.seriesLimit ?? undefined,
       };
     case DisplayType.StackedBar:
       return {
@@ -316,6 +316,7 @@ const convertToExternalTileChartConfig = (
           ? config.select.map(convertToExternalSelectItem)
           : [DEFAULT_SELECT_ITEM],
         numberFormat: config.numberFormat,
+        seriesLimit: config.seriesLimit ?? undefined,
       };
     case DisplayType.Number:
       return {
@@ -703,6 +704,7 @@ export function convertToInternalTileConfig(
           where: '',
           fillNulls: externalConfig.fillNulls === false ? false : undefined,
           seriesReturnType: externalConfig.asRatio ? 'ratio' : undefined,
+          seriesLimit: externalConfig.seriesLimit,
           name,
         } satisfies BuilderSavedChartConfig;
         break;
diff --git a/packages/api/src/utils/zod.ts b/packages/api/src/utils/zod.ts
index 42f11afeab..8c73d910d7 100644
--- a/packages/api/src/utils/zod.ts
+++ b/packages/api/src/utils/zod.ts
@@ -268,6 +268,7 @@ const externalDashboardLineChartConfigSchema =
     displayType: z.literal('line'),
     compareToPreviousPeriod: z.boolean().optional(),
     fitYAxisToData: z.boolean().optional(),
+    seriesLimit: z.number().int().positive().optional(),
   });
 
 const externalDashboardLineRawSqlChartConfigSchema =
@@ -282,6 +283,7 @@ const externalDashboardLineRawSqlChartConfigSchema =
 const externalDashboardBarChartConfigSchema =
   externalDashboardTimeChartConfigSchema.extend({
     displayType: z.literal('stacked_bar'),
+    seriesLimit: z.number().int().positive().optional(),
   });
 
 const externalDashboardBarRawSqlChartConfigSchema =