Costa, who represented Brazil in two friendlies before pledging his international loyalty to Spain, where he plays for Atletico Madrid, started against Italy on Wednesday as his new team won 1-0.
While Costa played the full 90 minutes in the Spanish capital, the 25-year-old struggled to make an impact with Spain's possession-based style significantly different to Atletico's game-plan.
But speaking after the friendly match, Del Bosque said Costa will adapt to Spain's style in the long run.
"It's good news. Little by little he's getting into the team dynamic," Del Bosque said.
The 63-year-old coach believes there is no reason why Costa cannot provide something for Spain: "There isn't a single player who could be harmful for the play of Spain."
Spain won thanks to Pedro's 63rd-minute goal at the Estadio Vicente Calderon - Atletico's home ground - and Del Bosque was generally pleased with his team's performance.
"We've moved the ball around well and we were slightly superior to Italy," Del Bosque said.
"Given it was a friendly, we've had some very good moments. We had some spells of great play, even though they too have had their chances.
"We've been lively with our play, we made the ball do the work and our circulation has been good.
"We've also been attentive defensively, to the advances of Italy when they've attacked."
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