Why use it
OpenAI Codex is a coding agent that lives in your terminal. By connecting Letterly, you give it access to your voice notes — meeting decisions, architecture ideas, product specs, anything you’ve dictated.
Instead of re-explaining context every session, just ask Codex to check your notes.
Setup
Add Letterly to your Codex MCP configuration. Create or edit ~/.codex/config.json:
{
"mcpServers": {
"letterly": {
"type": "streamable-http",
"url": "https://mcp.letterly.app/mcp"
}
}
}Restart Codex after saving. Sign in to Letterly when prompted on first use.
Try these prompts
Check my notes for the payment service requirements and implement the webhook handler
Find what I recorded about the API rate limiting approach and add it to this service
Save a note: the user onboarding flow needs a skip option for the tutorial, users are dropping off at step 3
Search my notes for the database schema discussion and generate the Prisma models
Tips
- Spec-driven development. Dictate feature specs as voice notes, then ask Codex to implement them directly.
- Decision log. Record why you chose a particular approach. When revisiting code later, Codex can find the reasoning.
- Bug context. Record details about a bug when you spot it. Ask Codex to find that note and fix the issue later.
Learn more
- Full technical reference — endpoint, tools, auth, scopes
- All MCP guides