diff --git a/lib/ai/vibn-tools.ts b/lib/ai/vibn-tools.ts
index 5a4d534c..a4ed0375 100644
--- a/lib/ai/vibn-tools.ts
+++ b/lib/ai/vibn-tools.ts
@@ -82,7 +82,7 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
         composeRaw: { type: 'STRING', description: 'Raw Docker Compose YAML for custom multi-service stacks. Only use when no template exists.' },
         repo: { type: 'STRING', description: 'Gitea repo name (e.g. "my-site") for deploying the user\'s own code.' },
         ports: { type: 'STRING', description: 'Port(s) the app listens on (e.g. "3000"). Required for repo/image pathways.' },
-        envs: { type: 'OBJECT', description: 'Environment variables as key-value pairs to inject at creation.' },
+        envsJson: { type: 'STRING', description: 'Environment variables as a JSON object string (e.g. \'{"KEY":"value"}\'). Optional.' },
         instantDeploy: { type: 'BOOLEAN', description: 'Whether to deploy immediately (default true).' },
       },
       required: ['name'],
@@ -95,9 +95,9 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
       type: 'OBJECT',
       properties: {
         uuid: { type: 'STRING', description: 'The Coolify application UUID.' },
-        patch: { type: 'OBJECT', description: 'Fields to update as key-value pairs.' },
+        patchJson: { type: 'STRING', description: 'Fields to update as a JSON object string (e.g. \'{"name":"new-name","ports_exposes":"3001"}\').' },
       },
-      required: ['uuid', 'patch'],
+      required: ['uuid', 'patchJson'],
     },
   },
   {
@@ -281,7 +281,11 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
       type: 'OBJECT',
       properties: {
         uuid: { type: 'STRING', description: 'The Coolify application UUID.' },
-        domains: { type: 'ARRAY', description: 'Array of domain strings (e.g. ["myapp.mark.vibnai.com", "api.mark.vibnai.com"]).' },
+        domains: {
+          type: 'ARRAY',
+          description: 'Array of domain strings (e.g. ["myapp.mark.vibnai.com", "api.mark.vibnai.com"]).',
+          items: { type: 'STRING' },
+        },
         service: { type: 'STRING', description: 'For compose apps: the service to attach the domain to (e.g. "server"). Default: "server".' },
       },
       required: ['uuid', 'domains'],
@@ -365,9 +369,9 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
       type: 'OBJECT',
       properties: {
         uuid: { type: 'STRING', description: 'The Coolify database UUID.' },
-        patch: { type: 'OBJECT', description: 'Fields to update.' },
+        patchJson: { type: 'STRING', description: 'Fields to update as a JSON object string (e.g. \'{"name":"new-name","is_public":true}\').' },
       },
-      required: ['uuid', 'patch'],
+      required: ['uuid', 'patchJson'],
     },
   },
   {
@@ -425,7 +429,11 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
     parameters: {
       type: 'OBJECT',
       properties: {
-        names: { type: 'ARRAY', description: 'Array of domain names to check (e.g. ["myapp.com", "myapp.io"]). Max 25.' },
+        names: {
+          type: 'ARRAY',
+          description: 'Array of domain names to check (e.g. ["myapp.com", "myapp.io"]). Max 25.',
+          items: { type: 'STRING' },
+        },
         period: { type: 'NUMBER', description: 'Registration period in years (default 1). Note: .ai requires 2 years minimum.' },
       },
       required: ['names'],
@@ -468,7 +476,11 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
       properties: {
         domain: { type: 'STRING', description: 'The registered domain name (e.g. "myapp.com").' },
         appUuid: { type: 'STRING', description: 'Coolify app UUID to attach the domain to.' },
-        subdomains: { type: 'ARRAY', description: 'Subdomains to wire (default ["@", "www"]).' },
+        subdomains: {
+          type: 'ARRAY',
+          description: 'Subdomains to wire (default ["@", "www"]).',
+          items: { type: 'STRING' },
+        },
       },
       required: ['domain'],
     },
@@ -545,7 +557,7 @@ Auto-domain {name}.{workspace}.vibnai.com is assigned automatically.`,
       type: 'OBJECT',
       properties: {
         url: { type: 'STRING', description: 'The full URL to fetch (https preferred).' },
-        headers: { type: 'OBJECT', description: 'Optional HTTP headers as key-value pairs.' },
+        headersJson: { type: 'STRING', description: 'Optional HTTP headers as a JSON object string (e.g. \'{"Accept":"application/json"}\').' },
       },
       required: ['url'],
     },
@@ -574,6 +586,21 @@ export async function executeMcpTool(
   // Convert underscore tool name → dotted MCP action (apps_create → apps.create)
   const action = toolName.replace(/_/g, '.');
 
+  // Unpack JSON-string args (Gemini schemas can't represent free-form objects,
+  // so we accept *Json string fields and parse them server-side).
+  const params: Record<string, unknown> = { ...args };
+  for (const key of Object.keys(params)) {
+    if (key.endsWith('Json') && typeof params[key] === 'string') {
+      const realKey = key.slice(0, -4); // envsJson → envs, patchJson → patch
+      try {
+        params[realKey] = JSON.parse(params[key] as string);
+      } catch {
+        return JSON.stringify({ error: `Invalid JSON for ${key}` });
+      }
+      delete params[key];
+    }
+  }
+
   try {
     const res = await fetch(`${baseUrl}/api/mcp`, {
       method: 'POST',
@@ -581,7 +608,7 @@ export async function executeMcpTool(
         'Content-Type': 'application/json',
         Authorization: `Bearer ${mcpToken}`,
       },
-      body: JSON.stringify({ action, params: args }),
+      body: JSON.stringify({ action, params }),
     });
     const data = await res.json();
     return JSON.stringify(data.result ?? data.error ?? data, null, 2).slice(0, 8000);
@@ -655,7 +682,10 @@ async function executeGithubFile(args: Record<string, unknown>): Promise<string>
 
 async function executeHttpFetch(args: Record<string, unknown>): Promise<string> {
   const url = String(args.url || '');
-  const extraHeaders = (args.headers as Record<string, string>) || {};
+  let extraHeaders: Record<string, string> = {};
+  if (typeof args.headersJson === 'string') {
+    try { extraHeaders = JSON.parse(args.headersJson); } catch { /* ignore */ }
+  }
 
   if (!url.startsWith('http://') && !url.startsWith('https://')) {
     return JSON.stringify({ error: 'URL must start with http:// or https://' });