Here is the full list of all 30 Agent A: A puzzle in disguise achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
The old phone in the shoe trick eh!? Find a shoe phone
Give your new ally their favourite delicacy, prepared to perfection
Complete Agent A in less than 120 minutes
Complete all conversations with Günther
Give Günther (the crazy Norwegian bird) hiccups
Release your latest catch... HINT: not Ruby though
Collect the fish bones a second time
Deliver a surprise to Onyx and you'll have an ally for life
Shoot the gun range target 100 times
Complete all conversations with Trevor
Investigate Ruby's phone call records
Show us your DJ skills, scratch a record for 10 seconds
Sabotage Ruby's submarine
Find Ruby's submarine
Find every spider web in Agent A
Broadcast warning message to Agent B
Download Ruby's mission
Overflow the sink a second time
Uncover Ruby's mission
Sneak into Ruby's hideout
Make a 'Boing' sound 10 times quickly
Give Agent A an 'electrifying' hairdo
Hit the briefcase kill switch
Access the hidden pool door
Disarm the electric pool
Open a stone doorway
Disable the house alarm system
Look up glissando in a dictionary, you'll know what to do Agent... HINT: start from the marked key
Locate Ruby La Rouge
Infiltrate Ruby's secret lair