diff --git a/package-lock.json b/package-lock.json
index 2684320958..5573282e16 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10,6 +10,7 @@
                 "@stoplight/spectral-cli": "^6.16.1",
                 "@stoplight/spectral-core": "^1.23.1",
                 "@stoplight/spectral-functions": "^1.10.5",
+                "@stoplight/spectral-parsers": "^1.0.5",
                 "@stoplight/spectral-ref-resolver": "^1.0.5",
                 "@stoplight/spectral-ruleset-bundler": "^1.7.0",
                 "apache-arrow": "^21.1.0",
diff --git a/package.json b/package.json
index 4a0de8c5c2..da4909ca23 100644
--- a/package.json
+++ b/package.json
@@ -27,6 +27,7 @@
         "@stoplight/spectral-cli": "^6.16.1",
         "@stoplight/spectral-core": "^1.23.1",
         "@stoplight/spectral-functions": "^1.10.5",
+        "@stoplight/spectral-parsers": "^1.0.5",
         "@stoplight/spectral-ref-resolver": "^1.0.5",
         "@stoplight/spectral-ruleset-bundler": "^1.7.0",
         "apache-arrow": "^21.1.0",
diff --git a/tools/spectral/ipa/README.md b/tools/spectral/ipa/README.md
index e317e5d5a9..058b20e7e9 100644
--- a/tools/spectral/ipa/README.md
+++ b/tools/spectral/ipa/README.md
@@ -76,6 +76,48 @@ overrides:
          x-xgen-IPA-xxx-rule: 'off'
 ```
 
+#### Consumer-Provided Word Lists
+
+The casing rules `xgen-IPA-117-operation-summary-format` and `xgen-IPA-126-tag-names-should-use-title-case`
+use two configurable lists:
+
+- `ignoreList`: words allowed to keep their specific casing (e.g. acronyms such as `API`, `AWS`, `DNS`)
+- `grammaticalWords`: common words allowed to stay lowercase in titles (e.g. `and`, `or`, `the`)
+
+Both lists are passed to the rule functions through Spectral's native `functionOptions`. Consumers who
+extend the ruleset can provide their own lists by redeclaring the rule **in their own repository's
+`.spectral.yaml`**, without editing this package or waiting for a new release. This is done in the
+repository that _consumes_ the ruleset, not in this `openapi` repository — note the `extends` on the
+published package below:
+
+```yaml
+extends:
+  - '@mongodb/ipa-validation-ruleset'
+
+rules:
+  xgen-IPA-126-tag-names-should-use-title-case:
+    given: $.tags[?(@.name && @.name.length > 0)]
+    then:
+      function: IPA126TagNamesShouldUseTitleCase
+      functionOptions:
+        ignoreList:
+          - API
+          - AWS
+          # ...the words this repository needs
+        grammaticalWords:
+          - and
+          - or
+```
+
+Because Spectral requires the whole rule to be redeclared when overriding `functionOptions`, consumers own
+the complete lists for their repository. The lists defined in `IPA-117.yaml` and `IPA-126.yaml` are the
+package defaults consumers inherit when they don't override them.
+
+Since these word lists are driven by the OpenAPI specs of the consuming repositories, keeping copies of them
+in sync just to satisfy this repository's own validation would be a maintenance burden. For that reason both
+rules are turned `off` in `ipa-spectral.yaml`, so this repository's second layer of validation does not run
+them. The rule definitions and their tests are kept for development and remain available to consumers.
+
 ### CI/CD Integration
 
 #### GitHub Actions Example
diff --git a/tools/spectral/ipa/__tests__/ConsumerWordLists.test.js b/tools/spectral/ipa/__tests__/ConsumerWordLists.test.js
new file mode 100644
index 0000000000..24bef4e57f
--- /dev/null
+++ b/tools/spectral/ipa/__tests__/ConsumerWordLists.test.js
@@ -0,0 +1,101 @@
+import { describe, expect, it } from '@jest/globals';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import { Document, Spectral } from '@stoplight/spectral-core';
+import * as Parsers from '@stoplight/spectral-parsers';
+import { httpAndFileResolver } from '@stoplight/spectral-ref-resolver';
+import { bundleAndLoadRuleset } from '@stoplight/spectral-ruleset-bundler/with-loader';
+
+// Proof that consumers extending the ruleset can supply their own `ignoreList` and
+// `grammaticalWords` by redeclaring the rule with their own `functionOptions` — the
+// native Spectral mechanism — without editing this package. The lists in the shipped
+// rulesets remain the defaults consumers inherit; this repository disables the two rules
+// in ipa-spectral.yaml so it does not have to keep those consumer-owned lists in sync.
+async function runRuleWithOptions(ruleName, rulesetFile, functionOptions, document) {
+  const rulesetPath = path.join(__dirname, '../rulesets', rulesetFile);
+  const s = new Spectral({ resolver: httpAndFileResolver });
+  const ruleset = Object(await bundleAndLoadRuleset(rulesetPath, { fs, fetch })).toJSON();
+  const definition = ruleset.rules[ruleName].definition;
+  if (functionOptions) {
+    definition.then.functionOptions = functionOptions;
+  }
+  const scopedRuleset = { rules: { [ruleName]: definition } };
+  if (ruleset.aliases) {
+    scopedRuleset.aliases = ruleset.aliases;
+  }
+  s.setRuleset(scopedRuleset);
+  return s.run(JSON.stringify(document));
+}
+
+async function runFullRuleset(document) {
+  const rulesetPath = path.join(__dirname, '../ipa-spectral.yaml');
+  const s = new Spectral({ resolver: httpAndFileResolver });
+  const ruleset = Object(await bundleAndLoadRuleset(rulesetPath, { fs, fetch }));
+  s.setRuleset(ruleset);
+  // ipa-spectral.yaml declares path-based `overrides`, so Spectral requires the
+  // document to have a source assigned.
+  return s.run(new Document(JSON.stringify(document), Parsers.Json, 'openapi.json'));
+}
+
+describe('Consumer-provided word lists via functionOptions', () => {
+  describe('xgen-IPA-126-tag-names-should-use-title-case (ignoreList)', () => {
+    const document = { tags: [{ name: 'ACME Alerts' }] };
+
+    it('flags a consumer acronym that is not in the package ignoreList', async () => {
+      const errors = await runRuleWithOptions(
+        'xgen-IPA-126-tag-names-should-use-title-case',
+        'IPA-126.yaml',
+        null,
+        document
+      );
+      expect(errors).toHaveLength(1);
+      expect(errors[0].code).toEqual('xgen-IPA-126-tag-names-should-use-title-case');
+    });
+
+    it('accepts the consumer acronym once added to functionOptions', async () => {
+      const errors = await runRuleWithOptions(
+        'xgen-IPA-126-tag-names-should-use-title-case',
+        'IPA-126.yaml',
+        { ignoreList: ['ACME'], grammaticalWords: [] },
+        document
+      );
+      expect(errors).toHaveLength(0);
+    });
+  });
+
+  describe('xgen-IPA-117-operation-summary-format (grammaticalWords)', () => {
+    const document = { paths: { '/resource': { get: { summary: 'Return One Resource per Project' } } } };
+
+    it('flags a consumer grammatical word that is not in the package list', async () => {
+      const errors = await runRuleWithOptions('xgen-IPA-117-operation-summary-format', 'IPA-117.yaml', null, document);
+      expect(errors).toHaveLength(1);
+      expect(errors[0].code).toEqual('xgen-IPA-117-operation-summary-format');
+    });
+
+    it('accepts the consumer grammatical word once added to functionOptions', async () => {
+      const errors = await runRuleWithOptions(
+        'xgen-IPA-117-operation-summary-format',
+        'IPA-117.yaml',
+        { ignoreList: [], grammaticalWords: ['per'] },
+        document
+      );
+      expect(errors).toHaveLength(0);
+    });
+  });
+
+  // These rules are the second layer of validation this repository runs against its own
+  // OpenAPI files. Because their word lists are owned by the consuming repositories, they
+  // are turned off in ipa-spectral.yaml to avoid keeping the lists in sync here.
+  describe('vocabulary-based rules are disabled in ipa-spectral.yaml', () => {
+    it('does not run the consumer-owned casing rules', async () => {
+      const document = {
+        tags: [{ name: 'not title case' }],
+        paths: { '/resource': { get: { summary: 'return all resources.' } } },
+      };
+      const results = await runFullRuleset(document);
+      const codes = results.map((r) => r.code);
+      expect(codes).not.toContain('xgen-IPA-117-operation-summary-format');
+      expect(codes).not.toContain('xgen-IPA-126-tag-names-should-use-title-case');
+    });
+  });
+});