The channel description is not the video description
YouTube has two description fields, and they do different jobs. The channel description is the text in the channel header and on About. It tells a new visitor what the videos are. A video description sits on one upload and should restate that video's promise in the first lines.
The bio generator drafts the channel field from words you type. The video description generator drafts the per-video field, including a chapter stub you still have to fill in. Pasting one into the other hides the promise.
The first sentence has to name the videos
The channel page shows the start of the description before a viewer expands it. That opening sentence should say what you publish and who it is for. Links and a contact email are separate fields in YouTube Studio. Leading the description with a row of social URLs spends the visible line on addresses.
Add a detail only when you can point at it: the kind of video, the setup, the series name. Do not add an upload promise you will not keep. The generator leaves that line blank unless you type it.
The published cap is 1,000 characters
The YouTube Data API documents a maximum of 1,000 characters for a channel's snippet.description. The channel description checker on this site counts toward that figure and says when a paste is over it. A video description is capped at 5,000 bytes, which is a different counter. Emoji can cost more than one character. The counter in Studio wins if it disagrees.
A thousand characters is enough for the niche, who the videos are for, and where to start. It is not a brief for every video you have ever uploaded. Point at a playlist for that.
Then check it against the channel you already have
A draft in a notes app still has to match the videos a stranger sees. The channel audit fetches the public channel, including that description, along with the latest uploads. If the description does not say the niche, rewrite it before you film something new.
The free scan does not require an account. Paid plans keep the written fixes. Pro is $9 a month, Growth is $19, and Unlimited is $39. Auto fix, on Unlimited, can apply a title, description, and tags after you preview them. It does not change the channel description on its own. Cancel in Settings.
Questions
Where does the YouTube channel description show?
In the channel header and on the About tab. It is the channel's snippet description, not the description box on an individual video.
How long can a YouTube channel description be?
The YouTube Data API documents a maximum of 1,000 characters for snippet.description. A video description is a separate field with a 5,000-byte limit.
Can the channel audit see the description I draft here?
Only after you publish it. The audit reads the public channel. This generator does not upload the draft.