diff --git a/packages/core/src/utils/schemaValidator.test.ts b/packages/core/src/utils/schemaValidator.test.ts
new file mode 100644
index 0000000000..ecd10321d2
--- /dev/null
+++ b/packages/core/src/utils/schemaValidator.test.ts
@@ -0,0 +1,125 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect, it } from 'vitest';
+import { SchemaValidator } from './schemaValidator.js';
+
+describe('SchemaValidator', () => {
+  it('should allow any params if schema is undefined', () => {
+    const params = {
+      foo: 'bar',
+    };
+    expect(SchemaValidator.validate(undefined, params)).toBeNull();
+  });
+
+  it('rejects null params', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        foo: {
+          type: 'string',
+        },
+      },
+    };
+    expect(SchemaValidator.validate(schema, null)).toBe(
+      'Value of params must be an object',
+    );
+  });
+
+  it('rejects params that are not objects', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        foo: {
+          type: 'string',
+        },
+      },
+    };
+    expect(SchemaValidator.validate(schema, 'not an object')).toBe(
+      'Value of params must be an object',
+    );
+  });
+
+  it('allows schema with extra properties', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        example_enum: {
+          type: 'string',
+          enum: ['FOO', 'BAR'],
+          // enum-descriptions is not part of the JSON schema spec.
+          // This test verifies that the SchemaValidator allows the
+          // use of extra keywords, like this one, in the schema.
+          'enum-descriptions': ['a foo', 'a bar'],
+        },
+      },
+    };
+    const params = {
+      example_enum: 'BAR',
+    };
+
+    expect(SchemaValidator.validate(schema, params)).toBeNull();
+  });
+
+  it('allows custom format values', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        duration: {
+          type: 'string',
+          // See: https://cloud.google.com/docs/discovery/type-format
+          format: 'google-duration',
+        },
+        mask: {
+          type: 'string',
+          format: 'google-fieldmask',
+        },
+        foo: {
+          type: 'string',
+          format: 'something-totally-custom',
+        },
+      },
+    };
+    const params = {
+      duration: '10s',
+      mask: 'foo.bar,biz.baz',
+      foo: 'some value',
+    };
+    expect(SchemaValidator.validate(schema, params)).toBeNull();
+  });
+
+  it('allows valid values for known formats', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        today: {
+          type: 'string',
+          format: 'date',
+        },
+      },
+    };
+    const params = {
+      today: '2025-04-08',
+    };
+    expect(SchemaValidator.validate(schema, params)).toBeNull();
+  });
+
+  it('rejects invalid values for known formats', () => {
+    const schema = {
+      type: 'object',
+      properties: {
+        today: {
+          type: 'string',
+          format: 'date',
+        },
+      },
+    };
+    const params = {
+      today: 'this is not a date',
+    };
+    expect(SchemaValidator.validate(schema, params)).not.toBeNull();
+  });
+});
diff --git a/packages/core/src/utils/schemaValidator.ts b/packages/core/src/utils/schemaValidator.ts
index 9465896ec9..9c7376e4d9 100644
--- a/packages/core/src/utils/schemaValidator.ts
+++ b/packages/core/src/utils/schemaValidator.ts
@@ -9,7 +9,18 @@ import * as addFormats from 'ajv-formats';
 // Ajv's ESM/CJS interop: use 'any' for compatibility as recommended by Ajv docs
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 const AjvClass = (AjvPkg as any).default || AjvPkg;
-const ajValidator = new AjvClass();
+const ajValidator = new AjvClass(
+  // See: https://ajv.js.org/options.html#strict-mode-options
+  {
+    // strictSchema defaults to true and prevents use of JSON schemas that
+    // include unrecognized keywords. The JSON schema spec specifically allows
+    // for the use of non-standard keywords and the spec-compliant behavior
+    // is to ignore those keywords. Note that setting this to false also
+    // allows use of non-standard or custom formats (the unknown format value
+    // will be logged but the schema will still be considered valid).
+    strictSchema: false,
+  },
+);
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 const addFormatsFunc = (addFormats as any).default || addFormats;
 addFormatsFunc(ajValidator);