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I built a prompt library that lives inside Claude's composer

Reddit · Ok_Negotiation_2587 · August 14, 2026
A developer created AI Toolbox, a browser extension that adds a personal prompt library to Claude's composer interface, triggered by typing "//" to display a dropdown menu of saved prompts filtered by search. The extension supports prompts with variable blanks like {{name}} or {{tone}} that are filled through forms, and the same library is accessible in ChatGPT and Gemini, with the extension itself partially built using Claude Code. The extension is available free with a 2-prompt limit on the free plan, and includes a usage tracking feature that displays how frequently each prompt has been used.

Detailed Analysis

A Reddit user's post on r/ClaudeAI details the creation of AI Toolbox, a browser extension that embeds a personal prompt library directly into Claude's composer interface. The tool works by letting users type "//" to trigger a dropdown of saved prompts, sorted by recency of use, with support for filtering as the user types. A notable feature is the use of templated placeholders—variables like {{name}} or {{tone}}—that prompt users to fill in a small form before the finished text is inserted, rather than requiring manual editing of pasted text. The developer built the extension partly using Claude Code, meaning Claude was used to construct its own prompt-management integration, a detail the poster highlighted as a fitting bit of recursion for the subreddit's audience.

The motivation behind the tool speaks to a common friction point in daily AI usage: prompt reuse. The developer describes previously storing prompts in Notion and cycling through a tedious loop of tab-switching, searching, copying, and pasting, which twice resulted in an embarrassing error—sending a client email with a previous client's name still embedded in the text. This kind of small but consequential mistake is emblematic of a broader usability gap in how people interact with LLM chat interfaces: prompt libraries and reusable templates are not natively well-supported in most consumer AI products, forcing users to build ad hoc workarounds. The shift from freeform text editing to structured form-based variable insertion directly addresses this class of error by making the "editable" parts of a prompt explicit and unmissable.

Beyond the interface mechanics, the developer notes an unexpected side effect of adding usage-count tracking to each saved prompt: after accumulating over a hundred prompts, the counts revealed that only about twelve were actually used regularly. This kind of lightweight analytics feature turned out to be more valuable than anticipated, enabling the developer to prune a bloated library based on real usage data rather than guesswork. It's a small but telling example of how instrumenting personal AI workflows can surface behavioral patterns users aren't consciously aware of, and it underscores a broader theme in AI tooling: the tools people build around LLMs often reveal as much about human habits as they do about the models themselves.

More broadly, this project fits into a growing ecosystem of third-party extensions and utilities designed to patch gaps in official AI chat interfaces—prompt managers, prompt-chaining tools, session organizers, and cross-platform utilities that sync data across Claude, ChatGPT, and Gemini. The fact that AI Toolbox works across all three major chat platforms (rather than being Claude-exclusive) reflects the reality that many power users maintain workflows spanning multiple LLM providers rather than committing to a single vendor. It also reflects a maturing secondary market around foundation model products, where the core chat interface becomes a platform for extension developers rather than a closed, complete product. Anthropic's own investment in Claude Code as a capable coding agent is notable here too, since the developer's use of Claude Code to build Claude's own integration illustrates how agentic coding tools are increasingly used by independent developers to rapidly build and ship polished products, including browser extensions that interact with the very AI systems that helped create them.

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