Ontology is widely used in the computer domain to structure concepts that represent a view of world nowadays, which could formally specify semantic relationship among the terms. In this paper, we present coordination between agent crawlers based on ontology in Topic Specific Search Engines, and we try to measure understanding among them, relying on Formal Concept Analysis (FCA) instead of comparing the terms only. In literature, most papers on concept similarity in FCA are based on two different concepts in the same concept lattice, and whereas there is very little research related to different concept lattices or even different agents. We propose a novel method on concept similarity for computing the Concept-Concept similarity, the Concept-Ontology similarity and the Ontology-Ontology similarity, and at last we can deduce understanding among agent crawlers. Finally, we can guide the crawlers effectively in our Search Engine.