diff --git a/apps/web/src/app/api/tools/update-schema/route.ts b/apps/web/src/app/api/tools/update-schema/route.ts
new file mode 100644
index 0000000..75c189a
--- /dev/null
+++ b/apps/web/src/app/api/tools/update-schema/route.ts
@@ -0,0 +1,101 @@
+import { prisma } from '@tpmjs/db';
+import { type NextRequest, NextResponse } from 'next/server';
+
+export const runtime = 'nodejs';
+export const dynamic = 'force-dynamic';
+
+/**
+ * POST /api/tools/update-schema
+ * Update a tool's input schema (parameters field)
+ *
+ * This is called when a tool is executed and we discover its actual schema
+ * from the executor's /load-and-describe endpoint.
+ *
+ * Body:
+ * - toolId: The tool's database ID
+ * - inputSchema: The JSON Schema for the tool's input parameters
+ * - description: Optional updated description from the tool
+ */
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json();
+    const { toolId, inputSchema, description } = body;
+
+    if (!toolId) {
+      return NextResponse.json({ success: false, error: 'toolId is required' }, { status: 400 });
+    }
+
+    if (!inputSchema) {
+      return NextResponse.json(
+        { success: false, error: 'inputSchema is required' },
+        { status: 400 }
+      );
+    }
+
+    console.log('[Update Schema] Updating tool:', toolId);
+    console.log('[Update Schema] Schema properties:', Object.keys(inputSchema.properties || {}));
+
+    // Convert JSON Schema to our parameters format
+    // The parameters field stores an array of parameter objects
+    const parameters = [];
+    if (inputSchema.properties) {
+      for (const [name, prop] of Object.entries(inputSchema.properties)) {
+        const propDef = prop as { type?: string; description?: string };
+        parameters.push({
+          name,
+          type: propDef.type || 'string',
+          required: inputSchema.required?.includes(name) || false,
+          description: propDef.description || '',
+        });
+      }
+    }
+
+    // Update the tool in the database
+    const updateData: { parameters: typeof parameters; description?: string } = {
+      parameters,
+    };
+
+    // Only update description if provided and different
+    if (description) {
+      updateData.description = description;
+    }
+
+    const updatedTool = await prisma.tool.update({
+      where: { id: toolId },
+      data: updateData,
+      select: {
+        id: true,
+        exportName: true,
+        description: true,
+        parameters: true,
+      },
+    });
+
+    console.log('[Update Schema] Tool updated:', {
+      id: updatedTool.id,
+      exportName: updatedTool.exportName,
+      parameterCount: parameters.length,
+    });
+
+    return NextResponse.json({
+      success: true,
+      tool: updatedTool,
+    });
+  } catch (error) {
+    console.error('[Update Schema] Error:', error);
+
+    // Handle not found error
+    if (error instanceof Error && error.message.includes('Record to update not found')) {
+      return NextResponse.json({ success: false, error: 'Tool not found' }, { status: 404 });
+    }
+
+    return NextResponse.json(
+      {
+        success: false,
+        error: 'Failed to update tool schema',
+        message: error instanceof Error ? error.message : 'Unknown error',
+      },
+      { status: 500 }
+    );
+  }
+}