Buffer API + MCP vs Mixpost API + MCP

Buffer API + MCP

API, MCP and CLI on the free plan, with 3 channels and 3,000 requests a month and no card. 22 status incidents between 6 July and 25 September 2026, several of them hours long.

Mixpost API + MCP

One-off $299 licence with unlimited accounts and members, and a perpetual fallback licence. No API or MCP in the free Lite edition.

Buffer API + MCP

1. Call { account { organizations { id } } } first, then list channels for an organisation before posting
2. Include ... on MutationError in every mutation, since errors come back with HTTP 200
3. On 429, wait Retry-After plus a few seconds of jitter. The 429 itself doesn't cost quota
4. Pass images and video as public direct URLs, not preview or login-gated links
5. Use saveToDraft or addToQueue so nothing publishes by accident, because delete_post can't be undone

Mixpost API + MCP

1. Call list-workspaces first. Workspace endpoints sit under /api/{workspaceUuid}
2. Check MIXPOST_CORE_PATH. It's empty by default from Pro v7 but defaults to mixpost in older versions and Lite
3. Create the token as a Viewer-role user when the agent only needs to read
4. Use unschedule-post rather than delete-post when a person wants a post pulled back to draft
5. Expect HTTP 422 with an errors.limit entry when a Cloud plan limit is hit