The most effective evidence is a letter from a professional (a doctor, specialist nurse or social worker etc) that specifically references the descriptors you meet or activities where you struggle. Simply having a diagnosis is not enough. Having said that, plenty of people win their tribunal based on what they say at the hearing rather than new evidence from a doctor.

If you are asking a professional for evidence, send them How to write useful evidence for a Work Capability Assessment (WCA) application or appeal so they know what to do. 

Give yourself the best chance of succes by following all our advice on how to prepare for a work capability assessment tribunal.

Also consider writing a tribunal submission using our free tool. It sets out your case, just like an adviser would.