feat(email-footer) Add "sent with sim ai" for free users (#3515)

* Add "sent with sim ai" for free users

* Only add prompt injection on free tier

* Add try catch around billing info fetch

---------

Co-authored-by: Theodore Li <theo@sim.ai>

apps/sim/app/api/mothership/execute/route.ts

@@ -43,7 +43,7 @@ export async function POST(req: NextRequest) {
     const effectiveChatId = chatId || crypto.randomUUID()
     const [workspaceContext, integrationTools, userPermission] = await Promise.all([
       generateWorkspaceContext(workspaceId, userId),
-      buildIntegrationToolSchemas(),
+      buildIntegrationToolSchemas(userId),
       getUserEntityPermissions(userId, 'workspace', workspaceId).catch(() => null),
     ])
 

apps/sim/lib/copilot/chat-payload.test.ts

@@ -0,0 +1,103 @@
+/**
+ * @vitest-environment node
+ */
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+vi.mock('@sim/logger', () => ({
+  createLogger: vi.fn(() => ({
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  })),
+}))
+
+vi.mock('@/lib/billing/core/subscription', () => ({
+  getUserSubscriptionState: vi.fn(),
+}))
+
+vi.mock('@/lib/copilot/chat-context', () => ({
+  processFileAttachments: vi.fn(),
+}))
+
+vi.mock('@/lib/core/config/feature-flags', () => ({
+  isHosted: false,
+}))
+
+vi.mock('@/lib/mcp/utils', () => ({
+  createMcpToolId: vi.fn(),
+}))
+
+vi.mock('@/lib/workflows/utils', () => ({
+  getWorkflowById: vi.fn(),
+}))
+
+vi.mock('@/tools/registry', () => ({
+  tools: {
+    gmail_send: {
+      id: 'gmail_send',
+      name: 'Gmail Send',
+      description: 'Send emails using Gmail',
+    },
+    brandfetch_search: {
+      id: 'brandfetch_search',
+      name: 'Brandfetch Search',
+      description: 'Search for brands by company name',
+    },
+  },
+}))
+
+vi.mock('@/tools/utils', () => ({
+  getLatestVersionTools: vi.fn((input) => input),
+  stripVersionSuffix: vi.fn((toolId: string) => toolId),
+}))
+
+vi.mock('@/tools/params', () => ({
+  createUserToolSchema: vi.fn(() => ({ type: 'object', properties: {} })),
+}))
+
+import { getUserSubscriptionState } from '@/lib/billing/core/subscription'
+import { buildIntegrationToolSchemas } from '@/lib/copilot/chat-payload'
+
+const mockedGetUserSubscriptionState = getUserSubscriptionState as unknown as {
+  mockResolvedValue: (value: unknown) => void
+  mockRejectedValue: (value: unknown) => void
+  mockClear: () => void
+}
+
+describe('buildIntegrationToolSchemas', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('appends the email footer prompt for free users', async () => {
+    mockedGetUserSubscriptionState.mockResolvedValue({ isFree: true })
+
+    const toolSchemas = await buildIntegrationToolSchemas('user-free')
+    const gmailTool = toolSchemas.find((tool) => tool.name === 'gmail_send')
+
+    expect(getUserSubscriptionState).toHaveBeenCalledWith('user-free')
+    expect(gmailTool?.description).toContain('sent with sim ai')
+  })
+
+  it('does not append the email footer prompt for paid users', async () => {
+    mockedGetUserSubscriptionState.mockResolvedValue({ isFree: false })
+
+    const toolSchemas = await buildIntegrationToolSchemas('user-paid')
+    const gmailTool = toolSchemas.find((tool) => tool.name === 'gmail_send')
+
+    expect(getUserSubscriptionState).toHaveBeenCalledWith('user-paid')
+    expect(gmailTool?.description).toBe('Send emails using Gmail')
+  })
+
+  it('still builds integration tools when subscription lookup fails', async () => {
+    mockedGetUserSubscriptionState.mockRejectedValue(new Error('db unavailable'))
+
+    const toolSchemas = await buildIntegrationToolSchemas('user-error')
+    const gmailTool = toolSchemas.find((tool) => tool.name === 'gmail_send')
+    const brandfetchTool = toolSchemas.find((tool) => tool.name === 'brandfetch_search')
+
+    expect(getUserSubscriptionState).toHaveBeenCalledWith('user-error')
+    expect(gmailTool?.description).toBe('Send emails using Gmail')
+    expect(brandfetchTool?.description).toBe('Search for brands by company name')
+  })
+})

apps/sim/lib/copilot/chat-payload.ts

@@ -1,4 +1,5 @@
 import { createLogger } from '@sim/logger'
+import { getUserSubscriptionState } from '@/lib/billing/core/subscription'
 import { processFileAttachments } from '@/lib/copilot/chat-context'
 import { getCopilotToolDescription } from '@/lib/copilot/tool-descriptions'
 import { isHosted } from '@/lib/core/config/feature-flags'
@@ -44,11 +45,22 @@ export interface ToolSchema {
  * Shared by the interactive chat payload builder and the non-interactive
  * block execution route so both paths send the same tool definitions to Go.
  */
-export async function buildIntegrationToolSchemas(): Promise<ToolSchema[]> {
+export async function buildIntegrationToolSchemas(userId: string): Promise<ToolSchema[]> {
   const integrationTools: ToolSchema[] = []
   try {
     const { createUserToolSchema } = await import('@/tools/params')
     const latestTools = getLatestVersionTools(tools)
+    let shouldAppendEmailTagline = false
+
+    try {
+      const subscriptionState = await getUserSubscriptionState(userId)
+      shouldAppendEmailTagline = subscriptionState.isFree
+    } catch (error) {
+      logger.warn('Failed to load subscription state for copilot tool descriptions', {
+        userId,
+        error: error instanceof Error ? error.message : String(error),
+      })
+    }
 
     for (const [toolId, toolConfig] of Object.entries(latestTools)) {
       try {
@@ -59,6 +71,7 @@ export async function buildIntegrationToolSchemas(): Promise<ToolSchema[]> {
           description: getCopilotToolDescription(toolConfig, {
             isHosted,
             fallbackName: strippedName,
+            appendEmailTagline: shouldAppendEmailTagline,
           }),
           input_schema: userSchema as unknown as Record<string, unknown>,
           defer_loading: true,
@@ -118,7 +131,7 @@ export async function buildCopilotRequestPayload(
   let integrationTools: ToolSchema[] = []
 
   if (effectiveMode === 'build') {
-    integrationTools = await buildIntegrationToolSchemas()
+    integrationTools = await buildIntegrationToolSchemas(userId)
 
     // Discover MCP tools from workspace servers and include as deferred tools
     if (workflowId) {

apps/sim/lib/copilot/tool-descriptions.test.ts

@@ -6,6 +6,7 @@ describe('getCopilotToolDescription', () => {
     expect(
       getCopilotToolDescription(
         {
+          id: 'brandfetch_search',
           name: 'Brandfetch Search',
           description: 'Search for brands by company name',
           hosting: { apiKeyParam: 'apiKey' } as never,
@@ -19,6 +20,7 @@ describe('getCopilotToolDescription', () => {
     expect(
       getCopilotToolDescription(
         {
+          id: 'brandfetch_search',
           name: 'Brandfetch Search',
           description: 'Search for brands by company name',
           hosting: { apiKeyParam: 'apiKey' } as never,
@@ -32,6 +34,7 @@ describe('getCopilotToolDescription', () => {
     expect(
       getCopilotToolDescription(
         {
+          id: 'brandfetch_search',
           name: '',
           description: '',
           hosting: { apiKeyParam: 'apiKey' } as never,
@@ -40,4 +43,60 @@ describe('getCopilotToolDescription', () => {
       )
     ).toBe('brandfetch_search <note>API key is hosted by Sim.</note>')
   })
+
+  it.concurrent('appends the email tagline instruction for Gmail tools when enabled', () => {
+    expect(
+      getCopilotToolDescription(
+        {
+          id: 'gmail_send',
+          name: 'Gmail Send',
+          description: 'Send emails using Gmail',
+        },
+        { appendEmailTagline: true }
+      )
+    ).toBe(
+      'Send emails using Gmail <important>Always add the footer "sent with sim ai" to the end of the email body. Add 3 line breaks before the footer.</important>'
+    )
+  })
+
+  it.concurrent('appends the email tagline instruction for Outlook tools when enabled', () => {
+    expect(
+      getCopilotToolDescription(
+        {
+          id: 'outlook_send',
+          name: 'Outlook Send',
+          description: 'Send emails using Outlook',
+        },
+        { appendEmailTagline: true }
+      )
+    ).toBe(
+      'Send emails using Outlook <important>Always add the footer "sent with sim ai" to the end of the email body. Add 3 line breaks before the footer.</important>'
+    )
+  })
+
+  it.concurrent('does not append the email tagline instruction for non-email tools', () => {
+    expect(
+      getCopilotToolDescription(
+        {
+          id: 'brandfetch_search',
+          name: 'Brandfetch Search',
+          description: 'Search for brands by company name',
+        },
+        { appendEmailTagline: true }
+      )
+    ).toBe('Search for brands by company name')
+  })
+
+  it.concurrent('does not append the email tagline instruction when disabled', () => {
+    expect(
+      getCopilotToolDescription(
+        {
+          id: 'gmail_send_v2',
+          name: 'Gmail Send',
+          description: 'Send emails using Gmail',
+        },
+        { appendEmailTagline: false }
+      )
+    ).toBe('Send emails using Gmail')
+  })
 })

apps/sim/lib/copilot/tool-descriptions.ts

@@ -1,23 +1,36 @@
 import type { ToolConfig } from '@/tools/types'
 
 const HOSTED_API_KEY_NOTE = '<note>API key is hosted by Sim.</note>'
+const EMAIL_TAGLINE_NOTE =
+  '<important>Always add the footer "sent with sim ai" to the end of the email body. Add 3 line breaks before the footer.</important>'
+const EMAIL_TAGLINE_TOOL_IDS = new Set(['gmail_send', 'gmail_send_v2', 'outlook_send'])
 
 export function getCopilotToolDescription(
-  tool: Pick<ToolConfig, 'description' | 'hosting' | 'name'>,
+  tool: Pick<ToolConfig, 'description' | 'hosting' | 'id' | 'name'>,
   options?: {
     isHosted?: boolean
     fallbackName?: string
+    appendEmailTagline?: boolean
   }
 ): string {
   const baseDescription = tool.description || tool.name || options?.fallbackName || ''
+  const notes: string[] = []
 
-  if (!options?.isHosted || !tool.hosting) {
+  if (options?.isHosted && tool.hosting && !baseDescription.includes(HOSTED_API_KEY_NOTE)) {
+    notes.push(HOSTED_API_KEY_NOTE)
+  }
+
+  if (
+    options?.appendEmailTagline &&
+    EMAIL_TAGLINE_TOOL_IDS.has(tool.id) &&
+    !baseDescription.includes(EMAIL_TAGLINE_NOTE)
+  ) {
+    notes.push(EMAIL_TAGLINE_NOTE)
+  }
+
+  if (notes.length === 0) {
     return baseDescription
   }
 
-  if (baseDescription.includes(HOSTED_API_KEY_NOTE)) {
-    return baseDescription
-  }
-
-  return baseDescription ? `${baseDescription} ${HOSTED_API_KEY_NOTE}` : HOSTED_API_KEY_NOTE
+  return [baseDescription, ...notes].filter(Boolean).join(' ')
 }