perf(plugin-mcp): minify JSON in MCP tool responses (#15598)

### What?

Replaces `JSON.stringify(result, null, 2)` with `JSON.stringify(result)`
in all MCP tool response handlers — resource CRUD, global find/update,
auth tools, and job run.

### Why?

MCP tool responses are consumed by AI agents, not humans. Pretty-printed
JSON with 2-space indentation adds significant whitespace overhead that
inflates response size without benefit. For rich-text-heavy documents,
this reduces MCP response payload size by ~50%.

### How?

- Changed all `JSON.stringify(x, null, 2)` calls to `JSON.stringify(x)`
in MCP tool response code (12 source files)
- Code-generation files (`config.ts`, `job/create.ts`) are intentionally
unchanged — they produce human-readable source files
- Updated existing test assertions to match minified format
(`"key":"value"` instead of `"key": "value"`)
- Added dedicated `Minified JSON responses` test suite verifying JSON
blocks contain no indentation and are valid JSON

---------

Co-authored-by: Paul Popus <paul@payloadcms.com>

Author: jhb-dev

packages/plugin-mcp/src/mcp/tools/auth/auth.ts

@@ -39,7 +39,7 @@ export const authTool = (server: McpServer, req: PayloadRequest, verboseLogs: bo
         content: [
           {
             type: 'text' as const,
-            text: `# Authentication Status\n\n\`\`\`json\n${JSON.stringify(result, null, 2)}\n\`\`\``,
+            text: `# Authentication Status\n\n\`\`\`json\n${JSON.stringify(result)}\n\`\`\``,
           },
         ],
       }

packages/plugin-mcp/src/mcp/tools/auth/forgotPassword.ts

@@ -36,7 +36,7 @@ export const forgotPasswordTool = (
         content: [
           {
             type: 'text' as const,
-            text: `# Password Reset Email Sent\n\n**User:** ${email}\n**Collection:** ${collection}\n**Email Disabled:** ${disableEmail}\n\n\`\`\`json\n${JSON.stringify(result, null, 2)}\n\`\`\``,
+            text: `# Password Reset Email Sent\n\n**User:** ${email}\n**Collection:** ${collection}\n**Email Disabled:** ${disableEmail}\n\n\`\`\`json\n${JSON.stringify(result)}\n\`\`\``,
           },
         ],
       }

packages/plugin-mcp/src/mcp/tools/auth/login.ts

@@ -40,7 +40,7 @@ export const loginTool = (server: McpServer, req: PayloadRequest, verboseLogs: b
         content: [
           {
             type: 'text' as const,
-            text: `# Login Successful\n\n**User:** ${email}\n**Collection:** ${collection}\n\n\`\`\`json\n${JSON.stringify(result, null, 2)}\n\`\`\``,
+            text: `# Login Successful\n\n**User:** ${email}\n**Collection:** ${collection}\n\n\`\`\`json\n${JSON.stringify(result)}\n\`\`\``,
           },
         ],
       }

packages/plugin-mcp/src/mcp/tools/auth/resetPassword.ts

@@ -29,7 +29,7 @@ export const resetPasswordTool = (server: McpServer, req: PayloadRequest, verbos
         content: [
           {
             type: 'text' as const,
-            text: `# Password Reset Successful\n\n**Collection:** ${collection}\n**Token:** ${token}\n\n\`\`\`json\n${JSON.stringify(result, null, 2)}\n\`\`\``,
+            text: `# Password Reset Successful\n\n**Collection:** ${collection}\n**Token:** ${token}\n\n\`\`\`json\n${JSON.stringify(result)}\n\`\`\``,
           },
         ],
       }

packages/plugin-mcp/src/mcp/tools/auth/unlock.ts

@@ -30,7 +30,7 @@ export const unlockTool = (server: McpServer, req: PayloadRequest, verboseLogs:
         content: [
           {
             type: 'text' as const,
-            text: `# User Account Unlocked\n\n**User:** ${email}\n**Collection:** ${collection}\n\n\`\`\`json\n${JSON.stringify(result, null, 2)}\n\`\`\``,
+            text: `# User Account Unlocked\n\n**User:** ${email}\n**Collection:** ${collection}\n\n\`\`\`json\n${JSON.stringify(result)}\n\`\`\``,
           },
         ],
       }

packages/plugin-mcp/src/mcp/tools/global/find.ts

@@ -81,7 +81,7 @@ export const findGlobalTool = (
             type: 'text' as const,
             text: `Global "${globalSlug}":
 \`\`\`json
-${JSON.stringify(result, null, 2)}
+${JSON.stringify(result)}
 \`\`\``,
           },
         ],

packages/plugin-mcp/src/mcp/tools/global/update.ts

@@ -120,7 +120,7 @@ export const updateGlobalTool = (
             type: 'text' as const,
             text: `Global "${globalSlug}" updated successfully!
 \`\`\`json
-${JSON.stringify(result, null, 2)}
+${JSON.stringify(result)}
 \`\`\``,
           },
         ],

packages/plugin-mcp/src/mcp/tools/job/run.ts

@@ -79,7 +79,7 @@ export const runJob = async (
 
 ## Input Data
 \`\`\`json
-${JSON.stringify(input, null, 2)}
+${JSON.stringify(input)}
 \`\`\`
 
 ## Job Status
@@ -121,7 +121,7 @@ console.log('Job result:', result)
 
 ## Input Data Provided:
 \`\`\`json
-${JSON.stringify(input, null, 2)}
+${JSON.stringify(input)}
 \`\`\`
 
 ## Next Steps:

packages/plugin-mcp/src/mcp/tools/resource/create.ts

@@ -114,7 +114,7 @@ export const createResourceTool = (
             text: `Resource created successfully in collection "${collectionSlug}"!
 Created resource:
 \`\`\`json
-${JSON.stringify(result, null, 2)}
+${JSON.stringify(result)}
 \`\`\``,
           },
         ],

packages/plugin-mcp/src/mcp/tools/resource/delete.ts

@@ -115,7 +115,7 @@ export const deleteResourceTool = (
               text: `Document deleted successfully from collection "${collectionSlug}"!
 Deleted document:
 \`\`\`json
-${JSON.stringify(result, null, 2)}
+${JSON.stringify(result)}
 \`\`\``,
             },
           ],
@@ -148,14 +148,14 @@ Errors: ${errors.length}
         if (docs.length > 0) {
           responseText += `\n\nDeleted documents:
 \`\`\`json
-${JSON.stringify(docs, null, 2)}
+${JSON.stringify(docs)}
 \`\`\``
         }
 
         if (errors.length > 0) {
           responseText += `\n\nErrors:
 \`\`\`json
-${JSON.stringify(errors, null, 2)}
+${JSON.stringify(errors)}
 \`\`\``
         }