Think First — Development skill for Claude Code

think-first

think-first makes Claude Code run a sequential-thinking step at the two moments where acting without a plan costs the most:

1. Before the first write in each turn. A turn starts with each new request, whether typed, sent with claude -p, sent from a phone, fired by a schedule, or sent by another session. A background task finishing doesn't start a new turn.
2. Before retrying a tool call that just failed. A plan made earlier in the turn doesn't cover a failure that came after it.

One successful thinking step covers every write in the turn and clears earlier failures.

What it needs

A sequential-thinking server. think-first checks that one was used; it doesn't bring its own. If you don't run one yet, add the standard one with a single command:

claude mcp add sequential-thinking -- npx -y @modelcontextprotocol/server-sequential-thinking@2025.11.25

think-first accepts any tool whose name ends in `sequentialthinking`. If none exists, it blocks writes and tells Claude to stop and say so, rather than letting them through.

**Why it doesn't bundle the server.** A plugin that brings its own server runs on your computer in Claude Cowork, and its check never reaches cloud Cowork tasks. Without the server, think-first runs inside the task, and Cowork passes it the thinking server from your computer while the desktop app is open.

Install

git clone https://github.com/shawnclybor/think-first.git
claude --plugin-dir ./think-first

`--plugin-dir` loads the plugin for that session only. Add the sequential-thinking server first (above).

Configure

Run `/plugin configure think-first`, then set:

Setting	Meaning	Default
writes	Which tools count as writes. Patterns are separated by ;. A glob uses *; /regex/flags matches anywhere in the tool name.	MCP tools whose names contain create, update, delete, send, post, publish, upload, move, remove, insert, execute, write, apply, deploy