[dsk139]

> concrete information (tasks, location, level, tech/tools, salary, business sector, team size...).

If location isn't implied the only reason you wouldn't give it is bad recruiting practices in your case. Salary/Tasks/Team Size could be changing pretty rapidly for startups and an external recruiter might not have the up to to date info. Companies do a bad job at investing in their external recruiting process. FWIW, I always provide company name, location, tech/tools, a hook about why I like them, and if I can find it a hook about the candidate.

> But that's the point: a phone call is a pretty big effort I think.

Switching jobs is a pretty big effort overall. A lot of engineers who are willing to take the step of taking a call are generally thinking about leaving or actively looking. For strong recruiters the message is just the hook. If you're able to find a few trusted tech recruiters you can use throughout your career it makes the overall search a lot easier every time. It's like finding the all-star real estate agent when you're buying a home. There are a lot of bad recruiters so in your case, it's more likely you haven't found a strong recruiter to work with yet.