From dfd30aecf12fc449a592a0c71b7af44cd2fec265 Mon Sep 17 00:00:00 2001
From: Matt Obee <mattobee@github.com>
Date: Thu, 27 Aug 2026 12:03:56 +0100
Subject: [PATCH 1/2] Add missing MCP scenario patterns

Keep the manually maintained catalogue in step with the eight scenario patterns published on primer.style.
---
 .changeset/update-mcp-scenario-patterns.md |  5 +++
 packages/mcp/src/primer.ts                 | 20 ++++++++++++
 packages/mcp/src/server.test.ts            | 37 ++++++++++++++++++++++
 packages/mcp/src/server.ts                 |  4 +--
 4 files changed, 64 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/update-mcp-scenario-patterns.md

diff --git a/.changeset/update-mcp-scenario-patterns.md b/.changeset/update-mcp-scenario-patterns.md
new file mode 100644
index 00000000000..e6d4868f36b
--- /dev/null
+++ b/.changeset/update-mcp-scenario-patterns.md
@@ -0,0 +1,5 @@
+---
+'@primer/mcp': minor
+---
+
+MCP server: Add Create, Delegate, Edit and View scenario patterns to the `list_patterns` and `get_pattern` tools.
diff --git a/packages/mcp/src/primer.ts b/packages/mcp/src/primer.ts
index 6a1dfbb13a8..a34d09c9d7b 100644
--- a/packages/mcp/src/primer.ts
+++ b/packages/mcp/src/primer.ts
@@ -51,11 +51,26 @@ const patterns: Array<Pattern> = [
     name: 'Copy',
     category: 'scenario',
   },
+  {
+    id: 'create',
+    name: 'Create',
+    category: 'scenario',
+  },
+  {
+    id: 'delegate',
+    name: 'Delegate',
+    category: 'scenario',
+  },
   {
     id: 'delete',
     name: 'Delete',
     category: 'scenario',
   },
+  {
+    id: 'edit',
+    name: 'Edit',
+    category: 'scenario',
+  },
   {
     id: 'filter',
     name: 'Filter',
@@ -66,6 +81,11 @@ const patterns: Array<Pattern> = [
     name: 'Search',
     category: 'scenario',
   },
+  {
+    id: 'view',
+    name: 'View',
+    category: 'scenario',
+  },
   {
     id: 'data-visualization',
     name: 'Data Visualization',
diff --git a/packages/mcp/src/server.test.ts b/packages/mcp/src/server.test.ts
index a20e6a97429..2005946bbf4 100644
--- a/packages/mcp/src/server.test.ts
+++ b/packages/mcp/src/server.test.ts
@@ -72,6 +72,43 @@ describe('MCP server', () => {
     )
   })
 
+  it('lists every published scenario pattern', async () => {
+    const result = await client.callTool({name: 'list_patterns'})
+    const scenarioPatterns = ['Copy', 'Create', 'Delegate', 'Delete', 'Edit', 'Filter', 'Search', 'View']
+
+    expect(result.content).toContainEqual(
+      expect.objectContaining({
+        type: 'text',
+        text: expect.stringContaining(
+          `## Scenario patterns\n\n${scenarioPatterns.map(name => `- ${name}`).join('\n')}`,
+        ),
+      }),
+    )
+  })
+
+  it.each([
+    {name: 'Create', id: 'create'},
+    {name: 'Delegate', id: 'delegate'},
+    {name: 'Edit', id: 'edit'},
+    {name: 'View', id: 'view'},
+  ])('retrieves the $name scenario pattern from its published URL', async ({name, id}) => {
+    vi.mocked(fetch).mockResolvedValue(new Response(`<main><h1>${name}</h1></main>`))
+
+    const result = await client.callTool({
+      name: 'get_pattern',
+      arguments: {name},
+    })
+
+    expect(fetch).toHaveBeenCalledTimes(1)
+    expect(vi.mocked(fetch).mock.calls[0]?.[0].toString()).toBe(`https://primer.style/product/scenario-patterns/${id}`)
+    expect(result.content).toContainEqual(
+      expect.objectContaining({
+        type: 'text',
+        text: expect.stringContaining(`Here are the guidelines for the \`${name}\` pattern for Primer:`),
+      }),
+    )
+  })
+
   it('requires between 2 and 10 names', async () => {
     const tooFew = await callBatch(['Button'])
     const tooMany = await callBatch(Array.from({length: 11}, (_, index) => `Component${index}`))
diff --git a/packages/mcp/src/server.ts b/packages/mcp/src/server.ts
index f1e031a27ed..7fb21e7a897 100644
--- a/packages/mcp/src/server.ts
+++ b/packages/mcp/src/server.ts
@@ -441,7 +441,7 @@ ${text}`,
     'list_patterns',
     {
       description:
-        'List all of the patterns available from Primer React. Scenario patterns describe specific user tasks (copy, delete, filter, search). Prefer a scenario pattern when one fits the task, and fall back to the more generic UI patterns otherwise.',
+        'List all of the patterns available from Primer React. Scenario patterns describe specific user tasks. Prefer a scenario pattern when one fits the task, and fall back to the more generic UI patterns otherwise.',
       annotations: {readOnlyHint: true},
     },
     async () => {
@@ -471,7 +471,7 @@ ${ui.join('\n')}`,
     'get_pattern',
     {
       description:
-        'Get a specific pattern by name. Scenario patterns describe specific user tasks (copy, delete, filter, search). Prefer a scenario pattern when one fits the task, and fall back to the more generic UI patterns otherwise.',
+        'Get a specific pattern by name. Scenario patterns describe specific user tasks. Prefer a scenario pattern when one fits the task, and fall back to the more generic UI patterns otherwise.',
       inputSchema: z.object({
         name: z.string().describe('The name of the pattern to retrieve'),
       }),

From 416d3128bee9734a6d96867124ba3e0ac05b51bd Mon Sep 17 00:00:00 2001
From: Matt Obee <mattobee@github.com>
Date: Thu, 27 Aug 2026 12:38:17 +0100
Subject: [PATCH 2/2] Add Customize MCP pattern

---
 .changeset/update-mcp-scenario-patterns.md | 2 +-
 packages/mcp/src/primer.ts                 | 5 +++++
 packages/mcp/src/server.test.ts            | 3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/.changeset/update-mcp-scenario-patterns.md b/.changeset/update-mcp-scenario-patterns.md
index e6d4868f36b..b5b3729e80f 100644
--- a/.changeset/update-mcp-scenario-patterns.md
+++ b/.changeset/update-mcp-scenario-patterns.md
@@ -2,4 +2,4 @@
 '@primer/mcp': minor
 ---
 
-MCP server: Add Create, Delegate, Edit and View scenario patterns to the `list_patterns` and `get_pattern` tools.
+MCP server: Add Create, Customize, Delegate, Edit and View scenario patterns to the `list_patterns` and `get_pattern` tools.
diff --git a/packages/mcp/src/primer.ts b/packages/mcp/src/primer.ts
index a34d09c9d7b..55dd80cded6 100644
--- a/packages/mcp/src/primer.ts
+++ b/packages/mcp/src/primer.ts
@@ -56,6 +56,11 @@ const patterns: Array<Pattern> = [
     name: 'Create',
     category: 'scenario',
   },
+  {
+    id: 'customize',
+    name: 'Customize',
+    category: 'scenario',
+  },
   {
     id: 'delegate',
     name: 'Delegate',
diff --git a/packages/mcp/src/server.test.ts b/packages/mcp/src/server.test.ts
index 2005946bbf4..0e47205d692 100644
--- a/packages/mcp/src/server.test.ts
+++ b/packages/mcp/src/server.test.ts
@@ -74,7 +74,7 @@ describe('MCP server', () => {
 
   it('lists every published scenario pattern', async () => {
     const result = await client.callTool({name: 'list_patterns'})
-    const scenarioPatterns = ['Copy', 'Create', 'Delegate', 'Delete', 'Edit', 'Filter', 'Search', 'View']
+    const scenarioPatterns = ['Copy', 'Create', 'Customize', 'Delegate', 'Delete', 'Edit', 'Filter', 'Search', 'View']
 
     expect(result.content).toContainEqual(
       expect.objectContaining({
@@ -88,6 +88,7 @@ describe('MCP server', () => {
 
   it.each([
     {name: 'Create', id: 'create'},
+    {name: 'Customize', id: 'customize'},
     {name: 'Delegate', id: 'delegate'},
     {name: 'Edit', id: 'edit'},
     {name: 'View', id: 'view'},