Mickey Rooney celebrated his 81st anniversary in show business not long ago. “We were on the road two days after I was born, and I think I’ve been on the road ever since,” he says. You could call him a trouper, but the man’s been performing since the Harding administration. Show me the troupe that could keep up with him.

His cheeks have grown rounder, fuller since his heyday, and his eyes more narrow. When he smiles, he almost seems to wince – but he keeps smiling. “Stand back world / I’m coming through! / Nothing can stop me now!” he sings brusquely in his new show, like a man surrounded.

Mr. Rooney wears a tuxedo, and you won’t find a wrinkle in it. Where would it come from? He moves tentatively, changing direction by shuffling his feet in tiny increments, left-right, left-right, left-right. Never a tall man, he seems positively cherubic on the stage of the Irish Repertory Theatre, where “Let’s Put on a Show!” opened last night.

The lineup will be familiar to people who know Mr. Rooney’s life, or know this genre of show. Jokes lead into stories, which are mixed with tunes. (He brought a three-piece band with him.) Mr. Rooney’s innovation is to include plenty of songs he wrote, and to have his wife, Jan, join him.The result does not inspire.

“Is it not strange that desire should so many years outlive performance?” says Poins of prowling old Falstaff. Mr. Rooney has the desire, undimmed, no doubt about that. He’s not onstage for the whole show, but it runs close to two hours, and he plays it eight times a week. He loves the look of an audience.

The performance is still there, too, though it has changed. Mr. Rooney has been a kid vaudevillian, Andy Hardy, a song-and-dance man, a sharp character actor, and, for a time, the Biggest Actor in the World. A little coaxing is needed now with his voice, which is, oddly enough, a lot like Elaine Stritch’s. Mr. Rooney has good stories, and enough charm to make you not mind that he reads them off a video screen.

It helps to be favorably disposed when you see this show. In fact, if you aren’t favorably disposed, why bother? Mr. Rooney carries an immense nostalgic punch, some childhood tie for anybody above a certain age. The crowd seems happy to hear him dish about his backstage boyhood, his marriage to first wife, Ava Gardner, and his famous partnership with Judy Garland. To complete the memory-jogging, you’d want some clips of the old days, and a couple of songs. All of this the show supplies. It turns calamitous when it tries to supply anything else.

Mr. Rooney’s original songs can’t compete with the standards, so the show feels padded. (Though the writing in the stories can turn unexpectedly delicate, as in this youthful evocation: “Burlesque theaters were great playgrounds for a child. There were painted sets and multicolored costumes. And then there were the warm, bright lights.”)

When his wife turns up, the show falls into deeper confusion. She ap pears after intermission, in an aggressively sparkly blue ensemble, to bully her way through some showtunes. The immutable laws of showbiz suggest their comic banter ought to work: Mickey’s been married eight times, and she’s tall enough to kiss the top of his head without tiptoes. That’s comic gold, baby. But their rhythms jar. She’s doing cabaret; he’s doing, well, Mickey Rooney.

Then there’s the bow tie. At the show I saw, Mr. Rooney’s bowtie, which is clipped to his microphone, came unclipped, and dangled for a while at his navel. He fumbled with it for what felt like an hour. Mrs. Rooney vaguely tried to help but didn’t succeed; she didn’t stop her song to do it right.A stage manager finally saved the day, but not before I wondered if the spectacularly uncomfortable scene might be a brilliantly inventive deconstruction of the husband/wife routine. Anyway, it was a chance for comic improvisation, a missed one.

The most intentionally poignant moments of the show tend to be the clips from his personal hall of fame: Mickey as a spunky kid, Mickey palling around with Judy, Mickey in an ill-advised Japanese caricature. The camera loves his face, not least because he uses it to send energy to the four corners of the screen from some bottomless private supply.

Mickey perches on a stool at center stage during these episodes, facing the audience, silhouetted by images of his younger self. Every now and then he glances up to catch this moment or that, the way a Met security guard might browse while walking the beat.A moment before the lights come back up, he slides off the stool, and gets himself balanced on the stage.Time for the next act to begin.