diff --git a/packages/builtin-tool-agent-builder/src/systemRole.ts b/packages/builtin-tool-agent-builder/src/systemRole.ts
index bc25d4f8e0..8a3ee0fbfa 100644
--- a/packages/builtin-tool-agent-builder/src/systemRole.ts
+++ b/packages/builtin-tool-agent-builder/src/systemRole.ts
@@ -17,6 +17,28 @@ The injected context includes:
 You should use this context to understand the current state of the agent and available tools before making any modifications.
 </context_awareness>
 
+<identity_boundary>
+**You are always the Agent Configuration Assistant — never the agent being configured.**
+
+Your sole role is to help users build, configure, and optimize agents. You do not become or roleplay as any agent under any circumstances.
+
+**Interpreting ambiguous short inputs:**
+When a user's message is a short phrase that could be read as either (a) a request for service from a domain expert, or (b) a description of an agent to create/configure — always choose interpretation (b).
+
+Examples of ambiguous inputs that should be treated as configuration requests:
+- "健康助手，咨询健康问题" → The user wants to create/configure an agent titled "健康助手" (Health Assistant) for "咨询健康问题" (health consultation) — NOT asking you to give health advice.
+- "客服机器人，处理售后问题" → Configure a customer-service agent for post-sales issues — NOT asking you to handle after-sales queries yourself.
+- "旅行助手" → Create/configure a travel assistant agent — NOT asking you for travel tips.
+
+The distinction is simple: **you configure agents; you do not act as them.** If the user genuinely wants health/travel/customer-service help, they would be talking to those agents directly — not to you, the Agent Configuration Assistant.
+</identity_boundary>
+
+<skill_coexistence>
+When LobeHub skills appear in the system context (listed under \`<available_skills>\`), those skills provide task-execution capabilities (e.g., web search, calendar access, coding assistance). However, for all agent **configuration** tasks — updating the agent's model, system prompt, plugins, metadata, or any other settings — always use the Agent Builder tools directly (\`updateConfig\`, \`updatePrompt\`, \`installPlugin\`, etc.).
+
+Do not delegate agent configuration to a LobeHub skill, even if the skill's name or description appears to overlap. Agent Builder tools apply changes immediately and directly to the current agent's stored configuration; LobeHub skills do not modify agent configuration.
+</skill_coexistence>
+
 <capabilities>
 You have access to tools that can modify agent configurations:
 
@@ -142,6 +164,13 @@ Always adapt to user's language. Use natural descriptions, not raw field names.
 </configuration_knowledge>
 
 <examples>
+User: "健康助手，咨询健康问题" (short phrase — agent name + purpose)
+Action: Treat as a configuration request, NOT a health consultation. Follow the modification sequence:
+1. Use updateMeta to set identity: { avatar: "🏥", title: "健康助手", description: "专注于健康咨询的 AI 助手" }
+2. Use updateConfig to set a suitable model
+3. Use updatePrompt to write a system prompt for a health consultant
+Do NOT respond as a health assistant or provide health advice. You are configuring the agent on the left panel to become a health assistant.
+
 User: "帮我创建一个代码助手" / "Help me create a coding assistant"
 Action: Follow the modification sequence:
 1. First, use updateMeta to set identity: { avatar: "👨‍💻", title: "Code Assistant", description: "A helpful coding assistant for debugging and writing code" }
diff --git a/src/server/services/toolExecution/serverRuntimes/agentBuilder.ts b/src/server/services/toolExecution/serverRuntimes/agentBuilder.ts
new file mode 100644
index 0000000000..6ce6ff7596
--- /dev/null
+++ b/src/server/services/toolExecution/serverRuntimes/agentBuilder.ts
@@ -0,0 +1,362 @@
+import {
+  AgentBuilderIdentifier,
+  type GetAvailableModelsParams,
+  type InstallPluginParams,
+  type SearchMarketToolsParams,
+  type UpdateAgentConfigParams,
+  type UpdatePromptParams,
+} from '@lobechat/builtin-tool-agent-builder';
+import { builtinTools } from '@lobechat/builtin-tools';
+import { BRANDING_PROVIDER } from '@lobechat/business-const';
+import { modelsResultsPrompt } from '@lobechat/prompts';
+
+import { AgentModel } from '@/database/models/agent';
+import { PluginModel } from '@/database/models/plugin';
+import { AiInfraRepos } from '@/database/repositories/aiInfra';
+import { DiscoverService } from '@/server/services/discover';
+
+import { type ToolExecutionContext, type ToolExecutionResult } from '../types';
+import { type ServerRuntimeRegistration } from './types';
+
+const MAX_MODELS = 20;
+
+const handleError = (error: unknown, message: string): ToolExecutionResult => {
+  const err = error as Error;
+  return { content: `${message}: ${err.message}`, success: false };
+};
+
+export const agentBuilderRuntime: ServerRuntimeRegistration = {
+  factory: (context: ToolExecutionContext) => {
+    if (!context.userId || !context.serverDB) {
+      throw new Error('userId and serverDB are required for Agent Builder execution');
+    }
+
+    const agentModel = new AgentModel(context.serverDB, context.userId);
+    const pluginModel = new PluginModel(context.serverDB, context.userId);
+    const aiInfraRepos = new AiInfraRepos(context.serverDB, context.userId, {});
+    const discoverService = new DiscoverService();
+
+    return {
+      getAvailableModels: async (
+        params: GetAvailableModelsParams,
+      ): Promise<ToolExecutionResult> => {
+        try {
+          const allProviders = await aiInfraRepos.getAiProviderList();
+          const enabledProviders = allProviders.filter((p) => p.enabled);
+
+          // LobeHub provider first, then by sort order
+          enabledProviders.sort((a, b) => {
+            if (a.id === BRANDING_PROVIDER) return -1;
+            if (b.id === BRANDING_PROVIDER) return 1;
+            return (a.sort ?? 999) - (b.sort ?? 999);
+          });
+
+          // Apply optional provider filter
+          const filteredProviders = params.providerId
+            ? enabledProviders.filter((p) => p.id === params.providerId)
+            : enabledProviders;
+
+          const providerResults: Array<{
+            id: string;
+            models: Array<{
+              abilities?: {
+                files?: boolean;
+                functionCall?: boolean;
+                reasoning?: boolean;
+                vision?: boolean;
+              };
+              description?: string;
+              id: string;
+              name: string;
+            }>;
+            name: string;
+          }> = [];
+
+          let totalModels = 0;
+
+          for (const provider of filteredProviders) {
+            if (totalModels >= MAX_MODELS) break;
+
+            const enabledChatModels = await aiInfraRepos.getAiProviderModelList(provider.id, {
+              enabled: true,
+              type: 'chat',
+            });
+
+            const remaining = MAX_MODELS - totalModels;
+            const sliced = enabledChatModels.slice(0, remaining);
+
+            if (sliced.length === 0) continue;
+
+            providerResults.push({
+              id: provider.id,
+              models: sliced.map((m) => ({
+                abilities: (m.abilities as any) ?? undefined,
+                id: m.id,
+                name: m.displayName || m.id,
+              })),
+              name: provider.name || provider.id,
+            });
+
+            totalModels += sliced.length;
+          }
+
+          const xmlContent = modelsResultsPrompt(providerResults);
+          const summary = `Found ${providerResults.length} enabled provider(s) with ${totalModels} model(s).\n\n${xmlContent}`;
+
+          return {
+            content: summary,
+            state: { providers: providerResults },
+            success: true,
+          };
+        } catch (error) {
+          return handleError(error, 'Failed to get available models');
+        }
+      },
+
+      searchMarketTools: async (params: SearchMarketToolsParams): Promise<ToolExecutionResult> => {
+        try {
+          const response = await discoverService.getMcpList({
+            category: params.category,
+            pageSize: params.pageSize || 10,
+            q: params.query,
+          });
+
+          const tools = response.items.map((item) => ({
+            author: item.author,
+            description: item.description,
+            identifier: item.identifier,
+            name: item.name,
+            tags: item.tags,
+          }));
+
+          let summary = `Found ${response.totalCount} tool(s) in the marketplace.`;
+          if (params.query) {
+            summary = `Found ${response.totalCount} tool(s) matching "${params.query}".`;
+          }
+
+          const toolLines = tools
+            .map((t) => `- ${t.name} (${t.identifier})${t.description ? ': ' + t.description : ''}`)
+            .join('\n');
+
+          return {
+            content: `${summary}\n\n${toolLines}`,
+            state: { query: params.query, tools, totalCount: response.totalCount },
+            success: true,
+          };
+        } catch (error) {
+          return handleError(error, 'Failed to search market tools');
+        }
+      },
+
+      updateConfig: async (
+        params: UpdateAgentConfigParams,
+        ctx: ToolExecutionContext,
+      ): Promise<ToolExecutionResult> => {
+        const agentId = ctx.agentId;
+
+        if (!agentId) {
+          return {
+            content: 'No active agent found',
+            error: { message: 'No active agent found', type: 'NoAgentContext' },
+            success: false,
+          };
+        }
+
+        try {
+          const agent = await agentModel.getAgentConfigById(agentId);
+          if (!agent) {
+            return { content: `Agent "${agentId}" not found.`, success: false };
+          }
+
+          let rawConfig: any = params.config;
+          if (typeof rawConfig === 'string') {
+            try {
+              rawConfig = JSON.parse(rawConfig);
+            } catch {
+              rawConfig = undefined;
+            }
+          }
+          let rawMeta: any = params.meta;
+          if (typeof rawMeta === 'string') {
+            try {
+              rawMeta = JSON.parse(rawMeta);
+            } catch {
+              rawMeta = undefined;
+            }
+          }
+
+          let finalConfig = rawConfig ? { ...rawConfig } : {};
+          const updatedParts: string[] = [];
+
+          if (params.togglePlugin) {
+            const { pluginId, enabled } = params.togglePlugin;
+            const currentPlugins = (agent.plugins as string[] | null) || [];
+            const isEnabled = currentPlugins.includes(pluginId);
+            const shouldEnable = enabled !== undefined ? enabled : !isEnabled;
+
+            const newPlugins =
+              shouldEnable && !isEnabled
+                ? [...currentPlugins, pluginId]
+                : !shouldEnable && isEnabled
+                  ? currentPlugins.filter((id: string) => id !== pluginId)
+                  : currentPlugins;
+
+            finalConfig = { ...finalConfig, plugins: newPlugins };
+            updatedParts.push(`plugin ${pluginId} ${shouldEnable ? 'enabled' : 'disabled'}`);
+          }
+
+          if ('systemRole' in finalConfig && !('editorData' in finalConfig)) {
+            finalConfig = { ...finalConfig, editorData: null };
+          }
+
+          if (Object.keys(finalConfig).length > 0) {
+            await agentModel.updateConfig(agentId, finalConfig);
+            const nonPluginFields = Object.keys(finalConfig).filter((f) => f !== 'plugins');
+            if (nonPluginFields.length > 0) {
+              updatedParts.push(`config fields: ${nonPluginFields.join(', ')}`);
+            }
+          }
+
+          if (rawMeta && Object.keys(rawMeta).length > 0) {
+            await agentModel.update(agentId, rawMeta as Record<string, unknown>);
+            updatedParts.push(`meta fields: ${Object.keys(rawMeta).join(', ')}`);
+          }
+
+          if (updatedParts.length === 0) {
+            return { content: 'No fields to update.', state: { success: true }, success: true };
+          }
+
+          return {
+            content: `Successfully updated agent. Updated ${updatedParts.join('; ')}`,
+            state: { agentId, success: true },
+            success: true,
+          };
+        } catch (error) {
+          return handleError(error, 'Failed to update agent config');
+        }
+      },
+
+      updatePrompt: async (
+        params: UpdatePromptParams,
+        ctx: ToolExecutionContext,
+      ): Promise<ToolExecutionResult> => {
+        const agentId = ctx.agentId;
+
+        if (!agentId) {
+          return {
+            content: 'No active agent found',
+            error: { message: 'No active agent found', type: 'NoAgentContext' },
+            success: false,
+          };
+        }
+
+        try {
+          await agentModel.update(agentId, {
+            editorData: null,
+            systemRole: params.prompt,
+          } as Record<string, unknown>);
+
+          return {
+            content: params.prompt
+              ? `Successfully updated system prompt (${params.prompt.length} characters)`
+              : 'Successfully cleared system prompt',
+            state: { newPrompt: params.prompt, success: true },
+            success: true,
+          };
+        } catch (error) {
+          return handleError(error, 'Failed to update prompt');
+        }
+      },
+
+      installPlugin: async (
+        params: InstallPluginParams,
+        ctx: ToolExecutionContext,
+      ): Promise<ToolExecutionResult> => {
+        const agentId = ctx.agentId;
+
+        if (!agentId) {
+          return {
+            content: 'No active agent found',
+            error: { message: 'No active agent found', type: 'NoAgentContext' },
+            success: false,
+          };
+        }
+
+        const { identifier, source } = params;
+
+        if (source === 'official') {
+          if (builtinTools.some((t) => t.identifier === identifier)) {
+            // Builtin tools (lobe-web-browsing, lobe-image-generation, etc.) need no OAuth
+            try {
+              const agent = await agentModel.getAgentConfigById(agentId);
+              if (!agent) return { content: `Agent "${agentId}" not found.`, success: false };
+
+              const currentPlugins = (agent.plugins as string[] | null) || [];
+              if (!currentPlugins.includes(identifier)) {
+                await agentModel.updateConfig(agentId, {
+                  plugins: [...currentPlugins, identifier],
+                });
+              }
+              return {
+                content: `Successfully enabled "${identifier}" for agent "${agentId}"`,
+                state: { installed: true, pluginId: identifier, success: true },
+                success: true,
+              };
+            } catch (error) {
+              return handleError(error, 'Failed to enable builtin tool');
+            }
+          }
+
+          // OAuth-based tools (Klavis, LobehubSkill) cannot be installed in background context
+          return {
+            content: `Installing official integrations that require OAuth (Klavis, LobehubSkill) is not supported in background execution. Please install "${identifier}" from the Agent Builder UI instead.`,
+            error: { message: 'OAuth not available in background context', type: 'NotSupported' },
+            success: false,
+          };
+        }
+
+        // source === 'market' — MCP marketplace plugin
+        try {
+          const agent = await agentModel.getAgentConfigById(agentId);
+          if (!agent) {
+            return { content: `Agent "${agentId}" not found.`, success: false };
+          }
+
+          const existing = await pluginModel.findById(identifier);
+          if (!existing) {
+            let manifest: any;
+            try {
+              manifest = await discoverService.getMcpManifest({ identifier });
+            } catch {
+              // proceed without manifest if fetch fails; tool will be unusable until manifest loads
+            }
+            await pluginModel.create({ identifier, manifest: manifest as any, type: 'plugin' });
+          } else if (!existing.manifest) {
+            try {
+              const manifest = await discoverService.getMcpManifest({ identifier });
+              await pluginModel.update(identifier, { manifest: manifest as any });
+            } catch {
+              // best-effort backfill
+            }
+          }
+
+          const currentPlugins = (agent.plugins as string[] | null) || [];
+          if (!currentPlugins.includes(identifier)) {
+            await agentModel.updateConfig(agentId, {
+              plugins: [...currentPlugins, identifier],
+            });
+          }
+
+          return {
+            content: `Successfully enabled plugin "${identifier}" for agent "${agentId}"`,
+            state: { installed: true, pluginId: identifier, success: true },
+            success: true,
+          };
+        } catch (error) {
+          return handleError(error, 'Failed to install plugin');
+        }
+      },
+    };
+  },
+  identifier: AgentBuilderIdentifier,
+};
diff --git a/src/server/services/toolExecution/serverRuntimes/index.ts b/src/server/services/toolExecution/serverRuntimes/index.ts
index f63af9434a..e66b95e120 100644
--- a/src/server/services/toolExecution/serverRuntimes/index.ts
+++ b/src/server/services/toolExecution/serverRuntimes/index.ts
@@ -8,6 +8,7 @@
  */
 import type { ToolExecutionContext } from '../types';
 import { activatorRuntime } from './activator';
+import { agentBuilderRuntime } from './agentBuilder';
 import { agentDocumentsRuntime } from './agentDocuments';
 import { agentManagementRuntime } from './agentManagement';
 import { briefRuntime } from './brief';
@@ -48,6 +49,7 @@ const registerRuntimes = (runtimes: ServerRuntimeRegistration[]) => {
 
 // Register all server runtimes
 registerRuntimes([
+  agentBuilderRuntime,
   webBrowsingRuntime,
   cloudSandboxRuntime,
   calculatorRuntime,