diff --git a/docs/openapi.json b/docs/openapi.json
index f4a55534..6021ed84 100644
--- a/docs/openapi.json
+++ b/docs/openapi.json
@@ -8374,6 +8374,13 @@
                         "truncated": {
                           "type": "boolean",
                           "description": "True when more than 200 groups exist; only the first 200 are returned."
+                        },
+                        "ignored_filters": {
+                          "type": "array",
+                          "items": {
+                            "type": "string"
+                          },
+                          "description": "Requested filter keys that were not applied. Omitted when all filters are recognized; the response remains HTTP 200 for compatibility."
                         }
                       }
                     }
diff --git a/packages/mcp/src/mcp.test.ts b/packages/mcp/src/mcp.test.ts
index 21da2daa..5dd48008 100644
--- a/packages/mcp/src/mcp.test.ts
+++ b/packages/mcp/src/mcp.test.ts
@@ -1197,3 +1197,63 @@ describe('trade intelligence tools', () => {
     }
   });
 });
+
+describe('ignored-filter errors at the MCP server boundary', () => {
+  it.each(['list_containers', 'summarize_containers'])(
+    '%s exposes correction guidance without any result payload',
+    async (name) => {
+      const ignored = ['current_status', 'custom_fields.unknown'];
+      containersList.mockResolvedValue({
+        items: [{ id: 'must-not-leak' }],
+        meta: { total: 99, ignored_filters: ignored },
+      });
+      containersSummary.mockResolvedValue({
+        groups: [{ key: 'must-not-leak', count: 99 }],
+        total: 99,
+        ignored_filters: ignored,
+      });
+      const { client, handler } = await connectClientForToolCall();
+      try {
+        const result = await client.callTool({
+          name,
+          arguments:
+            name === 'summarize_containers'
+              ? { group_by: 'current_status' }
+              : {},
+        });
+        expect(result.isError).toBe(true);
+        expect(result.structuredContent).toBeUndefined();
+        const text = JSON.stringify(result.content);
+        expect(text).toContain('current_status, custom_fields.unknown');
+        expect(text).toContain('Correct the filter names');
+        expect(text).toContain('do not silently remove');
+        expect(text).not.toContain('must-not-leak');
+        expect(text).not.toContain('applied_filters');
+      } finally {
+        await client.close();
+        await handler.close();
+      }
+    },
+  );
+
+  it('keeps malformed upstream diagnostics behind the generic error boundary', async () => {
+    containersList.mockResolvedValue({
+      items: [],
+      meta: { ignored_filters: ['private upstream message: secret'] },
+    });
+    const { client, handler } = await connectClientForToolCall();
+    try {
+      const result = await client.callTool({
+        name: 'list_containers',
+        arguments: {},
+      });
+      expect(result.isError).toBe(true);
+      expect(result.structuredContent).toBeUndefined();
+      expect(JSON.stringify(result.content)).toContain('Contact support');
+      expect(JSON.stringify(result)).not.toContain('private upstream');
+    } finally {
+      await client.close();
+      await handler.close();
+    }
+  });
+});
diff --git a/packages/mcp/src/tools/ignored-filters.test.ts b/packages/mcp/src/tools/ignored-filters.test.ts
new file mode 100644
index 00000000..4a0fa1bd
--- /dev/null
+++ b/packages/mcp/src/tools/ignored-filters.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vite-plus/test';
+import { Terminal49Client } from '@terminal49/sdk';
+import { executeListContainers } from './list-containers.js';
+import { executeSummarizeContainers } from './summarize-containers.js';
+
+// Exercise the real SDK mapping, not a mock that could mask dropped metadata.
+describe('container tools refuse ignored filters', () => {
+  for (const summary of [false, true]) {
+    for (const ignored of [undefined, [], ['current_status']]) {
+      it(`${summary ? 'summary' : 'list'} ${ignored?.length ? 'refuses ignored filters' : 'allows supported filters'}`, async () => {
+        const client = new Terminal49Client({
+          apiToken: 'TEST_KEY',
+          fetchImpl: async () =>
+            Response.json({
+              data: [],
+              meta: {
+                total: 0,
+                group_by: 'current_status',
+                truncated: false,
+                ...(ignored === undefined ? {} : { ignored_filters: ignored }),
+              },
+            }),
+        });
+        const result = summary
+          ? executeSummarizeContainers(
+              { group_by: 'current_status', current_status: ['available'] },
+              client,
+            )
+          : executeListContainers({ current_status: ['available'] }, client);
+        if (ignored?.length) {
+          await expect(result).rejects.toThrow(
+            'The container API did not apply these filters: current_status',
+          );
+        } else {
+          await expect(result).resolves.toBeDefined();
+        }
+      });
+    }
+  }
+});
diff --git a/packages/mcp/src/tools/ignored-filters.ts b/packages/mcp/src/tools/ignored-filters.ts
new file mode 100644
index 00000000..9d0b307e
--- /dev/null
+++ b/packages/mcp/src/tools/ignored-filters.ts
@@ -0,0 +1,22 @@
+import { ToolInputError } from './soft-results.js';
+
+/** Refuse results that the API could not scope to every requested filter. */
+export function assertNoIgnoredFilters(ignored: unknown): void {
+  if (ignored === undefined) return;
+  if (
+    !Array.isArray(ignored) ||
+    !ignored.every(
+      (key) => typeof key === 'string' && /^[a-zA-Z0-9_.-]{1,128}$/.test(key),
+    )
+  ) {
+    throw new Error(
+      'Invalid ignored_filters diagnostics from the container API; results were withheld.',
+    );
+  }
+  if (ignored.length > 0) {
+    // Only validated filter identifiers are exposed, never upstream error text.
+    throw new ToolInputError(
+      `The container API did not apply these filters: ${ignored.join(', ')}. Results were withheld to avoid presenting unfiltered data. Correct the filter names or account-specific custom field slugs and retry; do not silently remove the requested constraints.`,
+    );
+  }
+}
diff --git a/packages/mcp/src/tools/list-containers.ts b/packages/mcp/src/tools/list-containers.ts
index b10dfa33..399ce9d1 100644
--- a/packages/mcp/src/tools/list-containers.ts
+++ b/packages/mcp/src/tools/list-containers.ts
@@ -5,6 +5,7 @@
 
 import { Terminal49Client } from '@terminal49/sdk';
 import { logMcpEvent } from '../logging.js';
+import { assertNoIgnoredFilters } from './ignored-filters.js';
 import { compactContainer } from './compact-rows.js';
 
 const MAX_PAGE_SIZE = 25;
@@ -56,6 +57,8 @@ export async function executeListContainers(
       },
     );
 
+    assertNoIgnoredFilters(result?.meta?.ignored_filters);
+
     const duration = Date.now() - startTime;
     logMcpEvent({
       event: 'tool.execute.complete',
diff --git a/packages/mcp/src/tools/summarize-containers.ts b/packages/mcp/src/tools/summarize-containers.ts
index e8d1c062..8ccaa098 100644
--- a/packages/mcp/src/tools/summarize-containers.ts
+++ b/packages/mcp/src/tools/summarize-containers.ts
@@ -6,6 +6,7 @@
  */
 
 import { z } from 'zod';
+import { assertNoIgnoredFilters } from './ignored-filters.js';
 import { Terminal49Client } from '@terminal49/sdk';
 import { logMcpEvent } from '../logging.js';
 import {
@@ -65,6 +66,7 @@ export async function executeSummarizeContainers(
     const summary = await client.containers.summary(groupBy, filters as any, {
       format: 'mapped',
     });
+    assertNoIgnoredFilters(summary.ignored_filters);
     logMcpEvent({
       event: 'tool.execute.complete',
       tool: 'summarize_containers',
diff --git a/sdks/typescript-sdk/src/client.filters.test.ts b/sdks/typescript-sdk/src/client.filters.test.ts
index 79043915..47d46f44 100644
--- a/sdks/typescript-sdk/src/client.filters.test.ts
+++ b/sdks/typescript-sdk/src/client.filters.test.ts
@@ -569,3 +569,52 @@ describe('container summary response contract', () => {
     },
   );
 });
+
+describe('container ignored-filter diagnostics', () => {
+  for (const format of ['mapped', 'raw'] as const) {
+    it(`preserves summary diagnostics in ${format} format`, async () => {
+      const ignored = ['custom_fields.unknown'];
+      const { client } = clientFixture({
+        data: [{ key: 'available', label: 'available', count: 3 }],
+        meta: {
+          total: 3,
+          group_by: 'current_status',
+          truncated: false,
+          ignored_filters: ignored,
+        },
+      });
+      const result = await client.containers.summary(
+        'current_status',
+        {},
+        { format },
+      );
+      expect(
+        format === 'mapped'
+          ? result.ignored_filters
+          : result.meta.ignored_filters,
+      ).toEqual(ignored);
+    });
+    it(`preserves list diagnostics in ${format} format`, async () => {
+      const { client } = clientFixture({
+        data: [],
+        meta: { total: 0, ignored_filters: ['custom_fields.unknown'] },
+      });
+      const result = await client.containers.list({}, { format });
+      expect(result.meta.ignored_filters).toEqual(['custom_fields.unknown']);
+    });
+  }
+  it('rejects malformed summary diagnostics', async () => {
+    const { client } = clientFixture({
+      data: [],
+      meta: {
+        total: 0,
+        group_by: 'current_status',
+        truncated: false,
+        ignored_filters: 'unknown',
+      },
+    });
+    await expect(client.containers.summary('current_status')).rejects.toThrow(
+      'Invalid container summary response',
+    );
+  });
+});
diff --git a/sdks/typescript-sdk/src/client/managers/containers.ts b/sdks/typescript-sdk/src/client/managers/containers.ts
index 32211c8b..3aced739 100644
--- a/sdks/typescript-sdk/src/client/managers/containers.ts
+++ b/sdks/typescript-sdk/src/client/managers/containers.ts
@@ -64,7 +64,10 @@ function parseSummaryResponse(
     !Number.isSafeInteger(doc.meta.total) ||
     doc.meta.total < 0 ||
     doc.meta.group_by !== groupBy ||
-    typeof doc.meta.truncated !== 'boolean'
+    typeof doc.meta.truncated !== 'boolean' ||
+    (doc.meta.ignored_filters !== undefined &&
+      (!Array.isArray(doc.meta.ignored_filters) ||
+        !doc.meta.ignored_filters.every((key) => typeof key === 'string')))
   )
     throw invalid();
   const keys = new Set<string | null>();
@@ -191,6 +194,9 @@ export class ContainerManager extends BaseManager {
       total: doc.meta.total,
       groupBy: doc.meta.group_by,
       truncated: doc.meta.truncated,
+      ...(doc.meta.ignored_filters === undefined
+        ? {}
+        : { ignored_filters: doc.meta.ignored_filters }),
     }));
   }
 
diff --git a/sdks/typescript-sdk/src/generated/terminal49.ts b/sdks/typescript-sdk/src/generated/terminal49.ts
index aae7f902..b176108e 100644
--- a/sdks/typescript-sdk/src/generated/terminal49.ts
+++ b/sdks/typescript-sdk/src/generated/terminal49.ts
@@ -7197,6 +7197,8 @@ export interface operations {
                             group_by: "current_status" | "pod_terminal" | "shipping_line" | "port_of_discharge" | "hold_type" | "pickup_lfd_date" | "pod_arrival_date";
                             /** @description True when more than 200 groups exist; only the first 200 are returned. */
                             truncated: boolean;
+                            /** @description Requested filter keys that were not applied. Omitted when all filters are recognized; the response remains HTTP 200 for compatibility. */
+                            ignored_filters?: string[];
                         };
                     };
                 };