Postlint MCP server

Postlint is a small helper that answers one question: does this post fit? You paste a draft, tell your AI which platform it is for, and it tells you the exact counted length, the limit, and how much room is left. It is handy for anyone who writes social posts and has ever been surprised by a rejected or cut-off post.

What this MCP server does

You paste a draft post into your chat and say which platform it is for. Your AI passes the text to this helper. The helper counts it the way that platform actually counts, including the odd rules about links and emoji. Then it hands back a verdict: the counted length, the limit, how much room is left, and what pushed the count up. Nothing is posted anywhere. It only measures.

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What you can do with it

• Check one draft post against a single platform's limit
• Check the same draft against every supported platform at once
• See how much room you have left before you hit the limit
• See what drove the count, such as links being priced at a fixed length
• Look up each platform's limit and the unit it is counted in
• Catch a post that is over the limit before you publish it

Try asking your AI

• “Check this post for X and Bluesky and tell me if it fits”
• “How many characters is this draft on LinkedIn and Threads?”
• “This X post feels long, is it over 280?”
• “Show me the limits for all the platforms you support”

What it gives back to you

You get a short verdict in the chat. For one platform it shows the counted length, the limit, how much room is left, and a line explaining what drove the count, such as three links costing 23 each. For all platforms you get one row per platform, with the breakdown only on the rows that fail. It also warns you when a draft still has a placeholder like [URL] in it, because that count is only a floor.

Before you start

Who it's for

Social media managers, marketers, podcasters, founders and anyone who writes posts for several platforms and is tired of being caught by character limits.