Function executeMcpTool

apps/sim/tools/index.ts:1999–2208

* Execute an MCP tool via the server-side MCP endpoint * * @param toolId - MCP tool ID in format "mcp-serverId-toolName" * @param params - Tool parameters * @param executionContext - Execution context * @param requestId - Request ID for logging * @param startTimeISO - Start time for timing

(
  toolId: string,
  params: Record<string, any>,
  executionContext?: ExecutionContext,
  requestId?: string,
  startTimeISO?: string,
  signal?: AbortSignal
)

 * @param startTimeISO - Start time for timing
 */
async function executeMcpTool(
  toolId: string,
  params: Record<string, any>,
  executionContext?: ExecutionContext,
  requestId?: string,
  startTimeISO?: string,
  signal?: AbortSignal
): Promise<ToolResponse> {
  const actualRequestId = requestId || generateRequestId()
  const actualStartTime = startTimeISO || new Date().toISOString()

  try {
    logger.info(`[${actualRequestId}] Executing MCP tool: ${toolId}`)

    const { serverId, toolName } = parseMcpToolId(toolId)

    const baseUrl = getInternalApiBaseUrl()

    const mcpScope = resolveToolScope(params, executionContext)

    const headers: Record<string, string> = { 'Content-Type': 'application/json' }

    if (typeof window === 'undefined') {
      try {
        const internalToken = await generateInternalToken(mcpScope.userId)
        headers.Authorization = `Bearer ${internalToken}`
      } catch (error) {
        logger.error(`[${actualRequestId}] Failed to generate internal token:`, error)
      }
    }

    // Handle two different parameter structures:
    // 1. Direct MCP blocks: arguments are stored as JSON string in 'arguments' field
    // 2. Agent blocks: arguments are passed directly as top-level parameters
    let toolArguments = {}

    // First check if we have the 'arguments' field (direct MCP block usage)
    if (params.arguments) {
      if (typeof params.arguments === 'string') {
        try {
          toolArguments = JSON.parse(params.arguments)
        } catch (error) {
          logger.warn(`[${actualRequestId}] Failed to parse MCP arguments JSON:`, params.arguments)
          toolArguments = {}
        }
      } else {
        toolArguments = params.arguments
      }
    } else {
      // Agent block usage: extract MCP-specific arguments by filtering out system parameters
      toolArguments = Object.fromEntries(
        Object.entries(params).filter(([key]) => !MCP_SYSTEM_PARAMETERS.has(key))
      )
    }

    if (mcpScope.callChain && mcpScope.callChain.length > 0) {
      headers[SIM_VIA_HEADER] = serializeCallChain(mcpScope.callChain)
    }