I thought about an algorithm with weight adjustable by the user. Now, the API returns a field with the distance between the post and the query (the square of the Euclidean distance). It's used by the interface to rank results by relevance.

Perhaps I can compute a score for each story, where each field has a weight and rank the results using this score. For example, the score could be 0.2 x score + 0.1 x comments + 1/distance - timestamp/ 10^9. The stories with the highest rank would be shown first, and the weight (0.2, 0.1, 10^9) could be adjusted by the user, as some might prefer recency while others prefer popularity.