{"id":"https://openalex.org/W7155405965","doi":"https://doi.org/10.48550/arxiv.2604.19749","title":"The Tool-Overuse Illusion: Why Does LLM Prefer External Tools over Internal Knowledge?","display_name":"The Tool-Overuse Illusion: Why Does LLM Prefer External Tools over Internal Knowledge?","publication_year":2026,"publication_date":"2026-03-03","ids":{"openalex":"https://openalex.org/W7155405965","doi":"https://doi.org/10.48550/arxiv.2604.19749"},"language":null,"primary_location":{"id":"doi:10.48550/arxiv.2604.19749","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.19749","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"Preprint"},"type":"preprint","indexed_in":["datacite"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://doi.org/10.48550/arxiv.2604.19749","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5134408419","display_name":"Yirong Zeng","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Zeng, Yirong","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134365568","display_name":"Shen You","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"You, Shen","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134403335","display_name":"Yufei Liu","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Liu, Yufei","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134368522","display_name":"Qunyao Du","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Du, Qunyao","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134400608","display_name":"Xiao Ding","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Ding, Xiao","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5018432470","display_name":"Yutai Hou","orcid":"https://orcid.org/0000-0001-8660-1891"},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Hou, Yutai","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134384979","display_name":"Yuxian Wang","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Wang, Yuxian","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134388450","display_name":"Wu Ning","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Ning, Wu","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5053922312","display_name":"Hanwen Song","orcid":"https://orcid.org/0000-0001-9040-9026"},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Song, Haonan","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134450431","display_name":"Dandan Tu","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Tu, Dandan","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"middle","author":{"id":"https://openalex.org/A5134414323","display_name":"Bibo Cai","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Cai, Bibo","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]},{"author_position":"last","author":{"id":"https://openalex.org/A5134380763","display_name":"Ting Liu","orcid":null},"institutions":[],"countries":[],"is_corresponding":false,"raw_author_name":"Liu, Ting","raw_affiliation_strings":[],"raw_orcid":null,"affiliations":[]}],"institutions":[],"countries_distinct_count":0,"institutions_distinct_count":0,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":null,"has_fulltext":false,"cited_by_count":0,"citation_normalized_percentile":null,"cited_by_percentile_year":null,"biblio":{"volume":null,"issue":null,"first_page":null,"last_page":null},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10883","display_name":"Ethics and Social Impacts of AI","score":0.2053000032901764,"subfield":{"id":"https://openalex.org/subfields/3311","display_name":"Safety Research"},"field":{"id":"https://openalex.org/fields/33","display_name":"Social Sciences"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}},"topics":[{"id":"https://openalex.org/T10883","display_name":"Ethics and Social Impacts of AI","score":0.2053000032901764,"subfield":{"id":"https://openalex.org/subfields/3311","display_name":"Safety Research"},"field":{"id":"https://openalex.org/fields/33","display_name":"Social Sciences"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}},{"id":"https://openalex.org/T12026","display_name":"Explainable Artificial Intelligence (XAI)","score":0.1680999994277954,"subfield":{"id":"https://openalex.org/subfields/1702","display_name":"Artificial Intelligence"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11883","display_name":"Embodied and Extended Cognition","score":0.06360000371932983,"subfield":{"id":"https://openalex.org/subfields/2805","display_name":"Cognitive Neuroscience"},"field":{"id":"https://openalex.org/fields/28","display_name":"Neuroscience"},"domain":{"id":"https://openalex.org/domains/1","display_name":"Life Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/key","display_name":"Key (lock)","score":0.5422000288963318},{"id":"https://openalex.org/keywords/phenomenon","display_name":"Phenomenon","score":0.5249999761581421},{"id":"https://openalex.org/keywords/preference","display_name":"Preference","score":0.48339998722076416},{"id":"https://openalex.org/keywords/balance","display_name":"Balance (ability)","score":0.43630000948905945},{"id":"https://openalex.org/keywords/boundary","display_name":"Boundary (topology)","score":0.421999990940094},{"id":"https://openalex.org/keywords/causal-model","display_name":"Causal model","score":0.30630001425743103}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.5637000203132629},{"id":"https://openalex.org/C26517878","wikidata":"https://www.wikidata.org/wiki/Q228039","display_name":"Key (lock)","level":2,"score":0.5422000288963318},{"id":"https://openalex.org/C50335755","wikidata":"https://www.wikidata.org/wiki/Q483247","display_name":"Phenomenon","level":2,"score":0.5249999761581421},{"id":"https://openalex.org/C2781249084","wikidata":"https://www.wikidata.org/wiki/Q908656","display_name":"Preference","level":2,"score":0.48339998722076416},{"id":"https://openalex.org/C168031717","wikidata":"https://www.wikidata.org/wiki/Q1530280","display_name":"Balance (ability)","level":2,"score":0.43630000948905945},{"id":"https://openalex.org/C180747234","wikidata":"https://www.wikidata.org/wiki/Q23373","display_name":"Cognitive psychology","level":1,"score":0.4352000057697296},{"id":"https://openalex.org/C62354387","wikidata":"https://www.wikidata.org/wiki/Q875399","display_name":"Boundary (topology)","level":2,"score":0.421999990940094},{"id":"https://openalex.org/C154945302","wikidata":"https://www.wikidata.org/wiki/Q11660","display_name":"Artificial intelligence","level":1,"score":0.3984000086784363},{"id":"https://openalex.org/C107457646","wikidata":"https://www.wikidata.org/wiki/Q207434","display_name":"Human\u2013computer interaction","level":1,"score":0.3538999855518341},{"id":"https://openalex.org/C56739046","wikidata":"https://www.wikidata.org/wiki/Q192060","display_name":"Knowledge management","level":1,"score":0.3400000035762787},{"id":"https://openalex.org/C11671645","wikidata":"https://www.wikidata.org/wiki/Q5054567","display_name":"Causal model","level":2,"score":0.30630001425743103},{"id":"https://openalex.org/C15744967","wikidata":"https://www.wikidata.org/wiki/Q9418","display_name":"Psychology","level":0,"score":0.3043999969959259},{"id":"https://openalex.org/C115086926","wikidata":"https://www.wikidata.org/wiki/Q17004651","display_name":"Causal reasoning","level":3,"score":0.2935999929904938},{"id":"https://openalex.org/C2522767166","wikidata":"https://www.wikidata.org/wiki/Q2374463","display_name":"Data science","level":1,"score":0.27390000224113464},{"id":"https://openalex.org/C28427503","wikidata":"https://www.wikidata.org/wiki/Q13580300","display_name":"Internal model","level":3,"score":0.2732999920845032},{"id":"https://openalex.org/C2777211547","wikidata":"https://www.wikidata.org/wiki/Q17141490","display_name":"Training (meteorology)","level":2,"score":0.2612000107765198},{"id":"https://openalex.org/C119857082","wikidata":"https://www.wikidata.org/wiki/Q2539","display_name":"Machine learning","level":1,"score":0.2590999901294708}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.48550/arxiv.2604.19749","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.19749","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":null,"is_accepted":false,"is_published":null,"raw_source_name":null,"raw_type":"Preprint"}],"best_oa_location":{"id":"doi:10.48550/arxiv.2604.19749","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.2604.19749","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"Preprint"},"sustainable_development_goals":[],"awards":[],"funders":[],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":0,"referenced_works":[],"related_works":[],"abstract_inverted_index":{"Equipping":[0],"LLMs":[1],"with":[2],"external":[3],"tools":[4],"effectively":[5],"addresses":[6],"internal":[7,57,69],"reasoning":[8],"limitations.":[9],"However,":[10],"it":[11],"introduces":[12],"a":[13,63,86,113],"critical":[14],"yet":[15],"under-explored":[16],"phenomenon:":[17],"tool":[18,99,135,144,163,185],"overuse,":[19],"the":[20,124],"unnecessary":[21,162],"tool-use":[22,53,120],"during":[23,153],"reasoning.":[24],"In":[25],"this":[26,31,180],"paper,":[27],"we":[28,61,84,111,149,175],"first":[29],"reveal":[30],"phenomenon":[32],"is":[33],"pervasive":[34],"across":[35,55],"diverse":[36],"LLMs.":[37],"We":[38],"then":[39],"experimentally":[40],"elucidate":[41],"its":[42],"underlying":[43],"mechanisms":[44],"through":[45],"two":[46,181],"key":[47],"lenses:":[48],"(1)":[49],"First,":[50],"by":[51,102,122,137,165],"analyzing":[52],"behavior":[54,121],"different":[56],"knowledge":[58,70,79],"availability":[59],"regions,":[60],"identify":[62],"\\textit{knowledge":[64],"epistemic":[65,88],"illusion}:":[66],"models":[67],"misjudge":[68],"boundaries":[71],"and":[72,119,168],"fail":[73],"to":[74,183],"accurately":[75],"perceive":[76],"their":[77],"actual":[78],"availability.":[80],"To":[81,146],"mitigate":[82],"this,":[83,148],"propose":[85],"knowledge-aware":[87],"boundary":[89],"alignment":[90],"strategy":[91],"based":[92],"on":[93,158],"direct":[94],"preference":[95],"optimization,":[96],"which":[97],"reduces":[98],"usage":[100],"in":[101,179],"82.8\\%":[103],"while":[104],"yielding":[105],"an":[106],"accuracy":[107],"improvement.":[108],"(2)":[109],"Second,":[110],"establish":[112],"causal":[114],"link":[115],"between":[116],"reward":[117,151],"structures":[118],"visualizing":[123],"tool-augmented":[125],"training":[126,154],"process.":[127],"It":[128],"reveals":[129],"that":[130],"\\textit{outcome-only":[131],"rewards}":[132],"inadvertently":[133],"encourage":[134],"overuse":[136],"rewarding":[138],"only":[139],"final":[140],"correctness,":[141],"regardless":[142],"of":[143],"efficiency.":[145],"verify":[147],"balance":[150],"signals":[152],"rather":[155],"than":[156],"relying":[157],"outcome-only":[159],"rewards,":[160],"cutting":[161],"calls":[164],"66.7\\%":[166],"(7B)":[167],"60.7\\%":[169],"(32B)":[170],"without":[171],"sacrificing":[172],"accuracy.":[173],"Finally,":[174],"provide":[176],"theoretical":[177],"justification":[178],"lenses":[182],"understand":[184],"overuse.":[186]},"counts_by_year":[],"updated_date":"2026-07-01T06:00:48.157686","created_date":"2026-04-24T00:00:00"}