Function handleToolsList

apps/sim/app/api/mcp/serve/[serverId]/route.ts:539–678

(
  id: RequestId,
  serverId: string,
  rpcParams: unknown
)

)

async function handleToolsList(
  id: RequestId,
  serverId: string,
  rpcParams: unknown
): Promise<NextResponse> {
  try {
    const duplicateToolName = await getDuplicateToolName(serverId)
    if (duplicateToolName) {
      return NextResponse.json(
        createError(id, ErrorCode.InvalidRequest, 'MCP server has duplicate tool names', {
          code: 'duplicate_tool_name',
          toolName: duplicateToolName,
          recovery: 'Rename or remove duplicate workflow MCP tools before listing this server',
        }),
        { status: 409 }
      )
    }

    const cursor = getToolsListCursor(rpcParams)
    const pageCondition = cursor ? gt(workflowMcpTool.id, cursor) : undefined
    const toolSizes = await db
      .select({
        id: workflowMcpTool.id,
        toolNameBytes: sql<number>`octet_length(${workflowMcpTool.toolName})`,
        toolDescriptionBytes: sql<number>`coalesce(octet_length(${workflowMcpTool.toolDescription}), 0)`,
        parameterSchemaBytes: sql<number>`octet_length(${workflowMcpTool.parameterSchema}::text)`,
      })
      .from(workflowMcpTool)
      .where(
        and(
          eq(workflowMcpTool.serverId, serverId),
          isNull(workflowMcpTool.archivedAt),
          pageCondition
        )
      )
      .orderBy(asc(workflowMcpTool.id))
      .limit(MAX_MCP_TOOLS_LIST_COUNT + 1)

    const pageSizes = toolSizes.slice(0, MAX_MCP_TOOLS_LIST_COUNT)

    let estimatedSchemaBytes = 0
    let estimatedMetadataBytes = 0
    for (const toolSize of pageSizes) {
      estimatedSchemaBytes += Number(toolSize.parameterSchemaBytes) || 0
      estimatedMetadataBytes +=
        (Number(toolSize.toolNameBytes) || 0) +
        (Number(toolSize.toolDescriptionBytes) || 0) +
        (Number(toolSize.parameterSchemaBytes) || 0)
      assertKnownSizeWithinLimit(
        estimatedSchemaBytes,
        MAX_MCP_TOOLS_LIST_SCHEMA_BYTES,
        'MCP tools/list schemas'
      )
      assertKnownSizeWithinLimit(
        estimatedMetadataBytes,
        MAX_MCP_TOOLS_LIST_RESPONSE_BYTES,
        'MCP tools/list stored metadata'
      )