More than two dozen F.B.I. informants were in Washington on Jan. 6, 2021, but, contrary to widespread conspiracy theories, bureau officials did not instruct them to encourage anyone to break the law as a pro-Trump mob stormed the Capitol that day, according to a report by a Justice Department watchdog released on Thursday.

After a four-year investigation, the inspector general, Michael E. Horowitz, determined that F.B.I. leaders acted appropriately by dispatching some of the informants to monitor subjects related to the Capitol attack, and that the bureau shared the limited intelligence it had with other law enforcement agencies.

But the inspector general also criticized the bureau’s leaders for failing to recognize the potential dangers posed by the rioters — and for failing to follow through on its promise to canvass its field offices for intelligence on potential threats after the 2020 election.

Three of the informants had been sent to Washington on Jan. 6 “tasked by F.B.I. field offices to report on specific domestic terrorism case subjects,” the report found. One of them actually entered the Capitol during the riot, and the other two breached the “restricted area” around the building, investigators found.

But their reports were of limited of use and “no more specific” than other sources of information.

More than 20 other informants who had a history of working with the F.B.I. were in Washington that day and attended events related to Jan. 6, but went to them on their own volition, not at the bureau’s request, the report found.

The report found no evidence that any undercover F.B.I. agents were present in the crowd that gathered to disrupt the certification of President Biden’s electoral victory against Donald J. Trump in the 2020 election.