Function: core_memory_key_search
This tool belongs to the memory suite, which provides APIs to interact with a key-value based memory system. Tool description: Search for key names in the short-term memory that are similar to the query using BM25+ algorithm.
Parameters: query: type: string
description: The query text to search for.
k: type: integer
description: The number of results to return. 
default: 5
Required parameters: query
Response: ranked_results: type: array
description: A list of tuples containing the BM25+ score and the key.
items: type: array
items: float, string