The Best Free AI Persona for Writing and Editing
Which free CastMyAgent personas fit writing and editing work, who they suit, and how to start using one in three steps.
Short answer: For editing drafts, start with Sable, the Writing Coach persona on CastMyAgent, whose pack covers structure, prose editing, openings, pacing, and developmental feedback. For brand and content planning, Devon is the better match. Both are free and work in Claude, ChatGPT, and Gemini.
Who It's For
- Writers who want structured feedback on a draft, not a rewrite
- Marketers and founders planning content or messaging
- Anyone tired of AI edits that flatten their writing into generic prose
Which Personas Fit
Sable, Writing Coach. The main pick for editing. Her listed skills are narrative structure, prose editing, opening lines, pacing and rhythm, and developmental feedback. She starts by asking what your piece is about in one sentence, which is a useful discipline on its own.
Devon, Brand Content Strategist. Better for planning than line editing. Devon's pack covers brand voice development, content strategy, audience first writing, editorial planning, and narrative architecture.
Riley, Communications Director. For when the problem is positioning. Riley's pack covers creative positioning for founders who are too close to their product, turning jargon into stories, unexpected reframes, workshop facilitation, and narrative driven one pagers.
Models It Works With
The packs are plain text and work with Claude, ChatGPT, and Gemini. Put the production file in custom instructions (a Claude Project, a custom GPT, or a Gemini Gem) so it applies to every chat.
It's Free
All 19 walk-ons are free, and the persona text files are MIT licensed.
How to Use It in 3 Steps
- Pick by task. Editing a draft: Sable. Planning content: Devon. Fixing a pitch or one pager: Riley.
- Load the pack. Copy the production file from the persona's roster page into your model's custom instructions.
- Ask for feedback, not a rewrite. For example:
Here is a 900 word blog draft. Don't rewrite it.
Give me your top three structural problems, then
line level notes on the first two paragraphs only.
FAQ
Will the persona change my writing style? Only if you ask it to rewrite. Asking for notes keeps your draft yours.
Is a persona better than a plain "edit this" prompt? For a quick grammar pass, a plain prompt is fine. A persona helps when you want consistent, opinionated feedback across many drafts.
Can I combine personas? Use them in separate chats or projects. Mixing two production files in one prompt tends to blur both.
Do I need to pay for anything? No. The walk-ons are free.
Browse the roster at castmyagent.ai.