A number of studies have suggested the potentials of corpus tools in vocabulary learning. However, there are still some concerns. Corpus tools might be too complicated to use; example sentences retrieved from corpus tools might be too difficult to understand; processing large number of sample sentences could be challenging and time-consuming; also, not all English as a Foreign Language (EFL) learners know how to induct and deduct information from the concordance lines. So far, not much is known regarding how EFL writers actually perceive such tools as writing aids. To better understand this question, building on the same data set as the one published in 2015 (Lai & Chen, 2015), this study investigated students' perceptions of corpus tools right after they applied such tools to three writing tasks. Four online corpus tools, including monolingual and bilingual concordancers and collocation retrieval systems were provided along with two online dictionaries. After tool-training sections, students performed three timed-writing tasks online in three consecutive months and received individual recall interviews after each writing task. The interviews served as the major source of data. The analysis of the qualitative interview data revealed how the students perceived (1) the corpus tools as writing references, (2) the roles of the authentic example sentences, (3) the bilingual feature of the corpus tools, (4) the presentation of the corpus results, and (5) the features of the collocation retrieval system. Overall, the 14 students greatly valued corpus tools as writing references. The data also revealed how consulting the corpus helped the students to increase their confidence in writing, particularly in terms of wording. By eliciting students' perceptions and comments right after they integrated these tools into their writing tasks, the results obtained revealed not just writer perceptions but also on-site empirical data regarding how corpus tools contribute to EFL writing. [For full proceedings, see ED564162.]