Support calling a tool in instructions

[dgageot]

It would be useful to call a tool and inject its response into the instructions.
e.g we could read agents.md with the read_file tool.

We could leverage the existing code that replaces javascript placeholders.

Exact syntax TDB.

[aviralgarg05]

I would like to solve the issue, please assign me

[Pnkcaht]

Well, considering the issue had been unresolved for months and no one had responded, I resolved it. Thanks for the report :)

PR: #1482