JOINER, Senior District Judge, delivered the opinion of the court, in which KEITH, Circuit Judge, joined.
BATCHELDER, Circuit Judge (pp. 1347-50), delivered a separate dissenting opinion.
JOINER, Senior District Judge.Edwin Peavy appeals the summary dismissal of his motion to vacate sentence under 28 U.S.C. § 2255. We conclude that the factual record developed in the district court provided insufficient basis for the summary dismissal of Peavy’s motion. We therefore reverse and remand for an evidentiary hearing, subject to the limitations we delineate herein.
I.
A. Guilty Plea and Sentence
In 1989, Peavy was charged in a two-count indictment with cocaine distribution offenses under 21 U.S.C. § 841(a)(1). Peavy pled *1343guilty to one of the two counts pursuant to a plea agreement which set forth the applicable guidelines offense level and the parties’ agreement that “the role in offense adjustment, the obstruction adjustment, and the special career offender/criminal livelihood provisions are not applicable.” The written plea agreement makes no mention of any promise on Peavy’s part to cooperate in ongoing investigations. The agreement further states:
This is the entire Plea Agreement between the defendant and the United States of America and has been entered into by the defendant knowingly, freely, voluntarily, and without threats from anyone, after due consultation with his undersigned attorney. No alteration of any term of this Agreement may he made except as set forth in writing and agreed to by the parties.
(Emphasis added.)
At the plea hearing, Peavy was asked whether anyone promised him or threatened him to enter a guilty plea, and Peavy answered yes. The court then inquired whether there was a Rule 11 understanding, and Peavy again answered yes. At the court’s request, the assistant United States attorney recited the applicable sentencing terms, consistent with those set forth in the written plea agreement. The court then asked Peavy, “You understand that to be the Rule 11 agreement?” and Peavy answered yes. The court did not inquire whether there were any other promises or inducements.
At no time during the plea hearing did Peavy’s attorney or the assistant United States attorney disclose to the court that Peavy had agreed to cooperate with the government in exchange for sentencing concessions, and that court was to be informed of this cooperation at sentencing. Nonetheless, at sentencing, the court alluded to an in-ehambers conference during which Peavy’s cooperation with the government was disclosed. The court then sentenced Peavy to a term of 92 months, the lowest sentence in the applicable range, first noting that a higher sentence could have been applicable.
B. Post-Conviction Motions
Two years later, Peavy filed a motion to withdraw his plea under Fed.R.Crim.P. 32(d), alleging that prior to entering into the written plea agreement, he had been told by two FBI agents that if he cooperated in ongoing investigations, the United States attorney’s office would file a Rule 351 motion within a year of sentencing, seeking the reduction of his sentence, and that ultimately he would serve only two years of whatever sentence was imposed. Peavy further stated that the written plea agreement did not contain all of the agreed-upon terms because of a concern that Peavy’s safety and that of his wife and children would be. jeopardized if his cooperation became known. Peavy claimed that he cooperated as requested during this period, and that the government had breached the agreement. Peavy’s motion was supported by the affidavit of Peavy’s attorney, who had represented him at the plea and sentencing, and who claimed to have been present when the agents made the promise.
The government responded to Peavy’s Rule 32(d) motion, properly requesting that it be considered a § 2255 motion,2 and stating that the FBI agents denied that they made promises as alleged by Peavy and his counsel. The government’s response was neither verified nor supported by affidavits. In opposing Peavy’s motion, the government placed no reliance on the written plea agreement and the clause quoted above, and, in fact, stated that there was no written agreement between the parties. Instead, the government contended that an oral plea agreement required Peavy’s cooperation, and that the government had agreed to inform the court at sentencing of Peavy’s cooperation and to not seek any sentencing enhance*1344ments. The government claimed to have fully honored these obligations.
To support its assertion that the FBI agents did not make the disputed promises, the government explained a series of events that post-dated Peavy’s sentence. The government disclosed that Peavy’s cooperation had resulted in the indictments of four persons, three of whom had been tried and convicted by the time Peavy pled guilty. The fourth individual was apprehended later and tried in Detroit. Peavy’s cooperation was sought, but he did not testify at the trial. The Ohio assistant United States attorney told Peavy at the time that if the Michigan assistant United States attorney recommended a Rule 35 motion, that the Ohio office would “consider” such a request. The Michigan office made no recommendation, and the Ohio office made no motion. The government contended that the fact that Peavy’s counsel did not raise the alleged promises by the FBI agents while these matters were being discussed indicated that no promises were made.
Seven months later, when the court had not responded to the first motion, Peavy filed a motion to vacate, set aside or correct an order of sentence under 28 U.S.C. § 2255. This motion incorporated the earlier Rule 32 motion, and explained Peavy’s initial reluctance to testify at the Detroit trial of the fourth suspect. Peavy asserted that his wife had been warned that his service as an informant was known, and that he was justifiably concerned for his family’s safety. Peavy nonetheless agreed to testify, and was moved to the Detroit area several times, accompanied by counsel on at least one occasion. According to Peavy, the government concluded that his testimony was not needed.
The government responded to Peavy’s § 2255 motion by incorporating its response to the Rule 32 motion. Like its predecessor, this response was neither verified nor supported by affidavits. The court then entered a marginal entry order denying Peavy’s motion. Peavy moved to reconsider, stating that he was entitled to a hearing under § 2255, and arguing that the court disregarded the only evidence on the motion, the affidavit of his attorney.
The court denied the motion for reconsideration in an opinion, erroneously stating that Peavy’s written plea agreement contained an agreement to cooperate in exchange for the government’s promise to not seek sentencing enhancements. Placing exclusive reliance on the government’s unverified response, the court then detailed the cooperation rendered and the sentence imposed, as well as the government’s explanation of the Detroit trial and Peavy’s failure to testify at that trial. The court further stated that the FBI agents denied making the promises alleged by Peavy, although the record contained no affidavits setting forth this denial. The court stated that Peavy had presented no evidence to indicate that the government did not adhere to the plea agreement, and no evidence that the agents were authorized to make a deal with Peavy.
II.
Peavy requests alternative relief. First, he asks us to find that the government breached a promise which induced the guilty plea and to either enforce the promise or allow him to withdraw his plea. In the alternative, Peavy asks us to remand the case to the district court for a hearing, so that the factual issues can be resolved. Just as the record provided insufficient basis for the district court to find that Peavy’s plea was not induced by the FBI agents’ alleged promises, it is insufficient for this court to find the opposite. Thus, the principal issue is whether Peavy was entitled to a hearing. We also address Peavy’s claim that he is entitled to specific performance of the agents’ alleged promise.
A. Hearing
“A guilty plea, if induced by promises or threats which deprive it of the character of a voluntary act, is void. A conviction based upon such a plea is open to collateral attack.” Machibroda v. United States, 368 U.S. 487, 493, 82 S.Ct. 510, 513, 7 L.Ed.2d 473 (1962). “[W]hen a plea rests in any significant degree on a promise or agreement of the prosecutor, so that it can be said to be part of the inducement or consideration, such promise *1345must be fulfilled.” Santobello v. New York, 404 U.S. 257, 262, 92 S.Ct. 495, 499, 30 L.Ed.2d 427 (1971).
The proper procedure by which to challenge a federal plea-based conviction is pursuant to 28 U.S.C. § 2255, which provides in pertinent part:
Unless the motion and the files and records of the ease conclusively show that the prisoner is entitled to no relief, the court shall cause notice thereof to be served upon the United States attorney, grant a prompt hearing thereon, determine the issues and make findings of fact and conclusions of law with respect thereto.
(Emphasis added.) The critical question is whether the petitioner’s allegations, when viewed against the record of the plea hearing, are so “palpably incredible” or so “patently frivolous” as to warrant summary dismissal without a hearing. Blackledge v. Allison, 431 U.S. 63, 76, 97 S.Ct. 1621, 1630, 52 L.Ed.2d 136 (1977).
Blackledge assessed the need for a hearing against the record of the guilty plea which consisted of a printed form from which the trial judge asked questions and cheeked Blackledge’s “yes” or “no” answers. The Court noted that it was impossible to determine whether the trial court or counsel deviated from the form, and that the form did not reflect that either lawyer was asked to report any agreement that had been reached or sentencing recommendation that had been promised. In light of this record, the Court held that Blackledge’s claim that he was promised a specific sentence was not so frivolous as to warrant summary dismissal.
Unlike the situation in Blackledge, there was a written plea agreement in this case containing an integration clause, which, we emphasize, would ordinarily prevent any assertion that there were side deals or promises. However, the government places no reliance on the written plea agreement, and relies instead on an oral plea agreement. This oral agreement contained the same sentencing concessions identified by the government at the time of the plea, but went beyond the terms of the written agreement. The government describes this side agreement as one in which Peavy was to cooperate with the government and the government was to make this cooperation known to the court at the time of sentencing. Peavy has no quarrel with this characterization as far as it goes; however, he contends that the FBI agents promised him as well that a motion to reduce his sentence would be filed and that he would ultimately serve no more than two years of his term of imprisonment. The government denies that these promises were made. Even if we accept the government’s description of the oral agreement, however, the complete terms were never disclosed to the district court at the time of the plea.
The parties made no reference to a cooperation agreement during the plea hearing, and there is no evidence that the district court was aware of the agreement when it accepted Peavy’s plea. Contrary to the requirements of Fed.R.Crim.P. 11(d)3, the court did not ask Peavy whether there were any promises apart from the plea agreement. Such inquiry would have prompted disclosure of the promises on which Peavy relies here, or, if Peavy had remained silent, likely would foreclose his postconviction reliance on these promises. The court’s omission is not the sole cause of the incomplete record in this case, however, for the parties’ silence regarding Peavy’s cooperation agreement was deliberate.4
“[N]o procedural device for the taking of guilty pleas is so perfect in design and *1346exercise as to warrant a per se rule rendering it ‘uniformly invulnerable to subsequent challenge.’” Blackledge, 431 U.S. at 73, 97 S.Ct. at 1629 (quoting Fontaine v. United States, 411 U.S. 213, 215, 93 S.Ct. 1461, 1462, 36 L.Ed.2d 169 (1973)). Whether or not guilty pleas entered in accordance with Rule 11 are impervious to collateral attack is not the issue in this case, for whatever the benefits of the prophylactic measures prescribed by that rule, they can be of no assistance when they are deliberately circumvented. When the record of a plea is incomplete, we cannot draw meaningful inferences from the defendant’s silence on any given disputed issue of fact. For this reason, the record of Peavy’s guilty plea and sentencing in this case provides insufficient grounds on which to conclude that Peavy’s claims were subject to summary dismissal.
The evidence presented in connection with Peavy’s postconviction motions is likewise insufficient. The only evidence presented was the affidavit of Peavy’s counsel, who testified that he was present to hear the agents’ promises to Peavy. When presented with a record such as this, and a § 2255 motion supported by admissible evidence, the government must present evidence in support of its position. The unverified responses filed in this case were plainly inadequate. The district court’s factual findings in support of its dismissal of Peavy’s motion, based on the government’s responses, have no evidentiary support. We conclude that Peavy is entitled to an evidentiary hearing on his motion, and remand for this purpose.
In reaching this resolution, we remain mindful of the Supreme Court’s admonition that guilty pleas be accorded a “great measure of finality.” Blackledge, 431 U.S. at 71, 97 S.Ct. at 1628. To achieve that goal, the district court must take pains to ensure that all of the promises or assurances that the defendant claims to have received are disclosed. Fed.R.Crim.P. 11(d). Further, counsel for the government and the defendant must fully inform the court of all terms of the plea bargain, whether or not specifically asked. Safety and confidentiality concerns can and should be accommodated through in camera proceedings.
B. Relief Available
This court traditionally has analyzed the respective obligations of the parties under general principles of contract law. Because a guilty plea involves the waiver of fundamental constitutional rights, however, the analogy to a traditional contract is not complete, “and application of ordinary contract law principles to a plea agreement is not always appropriate.” United States v. Skidmore, 998 F.2d 372, 375 (6th Cir.1993). “Unlike the private contract situation, the validity of a bargained guilty plea depends finally upon the voluntariness and intelligence with which the defendant — and not his counsel — enters the bargained plea.” United States v. Harvey, 791 F.2d 294, 301 (4th Cir.1986) (citing Mabry v. Johnson, 467 U.S. 504, 509, 104 S.Ct. 2543, 2547, 81 L.Ed.2d 437 (1984)). When the prosecution breaches the plea agreement, the proper remedy may be either specific performance or permitting the defendant to withdraw his plea. Id.; Santobello v. New York, 404 U.S. 257, 262-63, 92 S.Ct. 495, 498-99, 30 L.Ed.2d 427 (1971). The choice between these remedies is not up to the defendant but, rather, rests in the sound discretion of the district court. Kingsley v. United States, 968 F.2d 109, 113 (1st Cir.1992).
The relief available to Peavy is limited by the terms of Rule 35, which permit the reduction of a sentence within a limited time, which, under the facts of this case, has long since passed. The government cannot now be required to file a delayed Rule 35 motion.5 While in appropriate circumstances a defendant may be entitled to specific performance of promises made by the government to induce a guilty plea, e.g., United States v. Canada, 960 F.2d 263 (1st Cir.1992), this is *1347not such a case. Further, we stress here that Peavy is not entitled to specific performance of the alleged promise that he would serve only two years of the sentence imposed by the district court. The FBI agents clearly had no authority, actual or apparent, to bind the district court, and it is not alleged that the court ratified or otherwise affirmed any such assurance.
Thus, the sole question is whether Peavy should be permitted to withdraw his plea. On remand, the district court must determine whether the FBI agents made promises to Peavy, and, if so, determine precisely what those promises were. Additionally, the court must determine whether the agents had the apparent authority to make the disputed promises on behalf of the government, taking into account the secrecy surrounding Peavy’s cooperation agreement, and whether Peavy relied to his detriment on the promises. See United States v. Streebing, 987 F.2d 368, 372-73 (6th Cir.) cert. denied, — U.S. -, 113 S.Ct. 2933, 124 L.Ed.2d 683 (1993). Ultimately, the court must determine whether Peavy’s plea was “a voluntary and intelligent choice among the alternative courses of action open to the defendant.” North Carolina v. Alford, 400 U.S. 25, 31, 91 S.Ct. 160, 164, 27 L.Ed.2d 162 (1970).
REVERSED and REMANDED for proceedings consistent with this opinion.
. In 1990, Fed.R.Crim.P. 35 provided that the "court, on motion of the Government, may within one year after the imposition of a sentence, lower a sentence to reflect a defendant’s subsequent, substantial assistance in the investigation or prosecution of another person who has committed an offensef.]”
. Rule 32(d) provides that after sentencing a "plea may be set aside only on direct appeal or by motion under 28 U.S.C. § 2255.”
. Rule 11(d) states in pertinent part:
Insuring that the Plea is Voluntary. The court shall not accept a plea of guilty or nolo contendere without first, by addressing the defendant personally in open court, determining that a plea is voluntary and not the result of force or threats or of promises apart from a plea agreement.
(Emphasis added.) The Bench Book for District Judges, 1.06A (3d ed.1993), recommends that the court not only confirm the terms of the plea agreement with the defendant, but also ask whether "anyone [has] made any other or different promise or assurance to you of any kind in an effort to induce you to enter a plea of guilty ... in this case[.] ”
. The government acknowledged the existence of Peavy's side cooperation agreement at oral argument and in correspondence to Peavy's attorney.
. United States v. Addonizio, 442 U.S. 178, 189, 99 S.Ct. 2235, 2242-43, 60 L.Ed.2d 805 (1979); Fed.R.Crim.P. 45(b); United States v. Taylor, 768 F.2d 114 (6th Cir.1985); United States v. Blanton, 739 F.2d 209 (6th Cir.1984). Cf. United States v. Davis, 992 F.2d 635 (6th Cir.), cert. denied, - U.S. -, 114 S.Ct. 265, 126 L.Ed.2d 217 (1993) (court lacks power to enter judgment of acquittal beyond the time provided in applicable rule).