It’s not, unless contexts get as large as comparable training materials. And you’d have to compile adequate materials. Clearly, just adding some documentation about $tool will not have the same effect as adding all the gigabytes of internet discussion and open source code regarding $tool that the model would otherwise have been trained on. This is similar to handing someone documentation and immediately asking questions about the tool, compared to asking someone who had years of experience with the tool.
Lastly, it’s also a huge waste of energy to feed the same information over and over again for each query.
You’re assuming that everything can be easily known from documentation. That’s far from the truth. A lot of what LLMs produce is informed by having been trained on large amounts of source code and large amounts of discussions where people have shared their knowledge from experience, which you can’t get from the documentation.