Clinton has stressed the need for better governance across Africa during visits to Kenya, South Africa, Angola, the Democratic Republic of Congo, Nigeria and Liberia.
"The Obama administration has delivered ... a message of tough love," she said.
"We are not sugarcoating the problems, we are not shying away from them, our emphasis is to help to channel the hopes and aspirations of the people of Africa, in a way that changes the direction of their countries."
Salim Lone, adviser to the Kenyan prime minister, told Al Jazeera that her visit had been a "huge success" for the US.
"She presented a wonderful new face of American policy after eight years of [President George] Bush. She won many people's hearts.
Lone said the US administration had delivered a message about the need for democracy but had not presented a programme for how it should be obtained.
"There seems to be an inherent contradiction between those ideas and at the same time a very close military and anti-terror co-operation which does not allow any room in those countries for dealing with civil society issues and opposition voices."
"The US seems to be rethinking, 'is it the right thing to press for good governance, democracy and clean elections, when other US interests require that you deal with governments because you need their oil or their military co-operation?'
"Mrs Clinton seems to be saying that whatever you in Kenya, you in Nigeria, you in Liberia, can do, we will support you but don't look to us for some concrete action."
Cape Verde is a tiny Portuguese-speaking Atlantic Ocean nation. About half a million Cape Verdeans live in the US, roughly as many as those still living on the islands.
Aides said Clinton chose to spend a night in Cape Verde - often only a brief refuelling stopover between Africa and North America - in an effort to boost relations with the small but close US ally.
Cape Verde will be the first country to successfully complete a loan from the Millennium Challenge Corp, a US government-backed initiative that lends money to democratic countries, a US official said.
It signed a $110m deal under the initiative in 2005 to boost its economy, including through infrastructure projects and investment in agriculture.
In a sign of its Western inclination, Cape Verde agreed to be the site in 2006 of Nato exercises.