It's been mentioned that magi can have books and other arcane belongings as personal property. I don't really see any rules for this. I'd think the flawed resources hook might work, but it provides 250 builds points, which is a bit much for a Spring covenant (and actually seems a bit high for a more senior magus). Also, there's no virtue to reflect this in character creation (since magi are forbidden from taking wealthy).
Covenants p.16 Hidden Resources can be used to model personal property of a covenant's NPC magi.
And there's HoH:TL p.106 Magic Items for Redcaps and HoH:MC p.135 Masterpiece for Verditius. You can extrapolate from there with your troupe. But such Virtues are hard to generalize and tend to frontload a PC magus, which is particularly awkward in a game focused on character development.
Cheers
But why not simply allow each magus a set number of Build Points worth of personal resources? Don't charge Virtues of Covenant Boons for this is everyone has it. Mind you, Personal Vis Source is a Virtue, but it is vague about the annual amount. If you decide what this is worth (we use as standard 4 pawns/year) see what this is worth in BP as a vis source, and use this to calculate worth of books or other property.
Please explain the situation you want this to factor in to.
Are you starting a Spring covenant and the individual magi have things belong to them personally which won't be a part of the covenant's resources?
The way we play it is indeed that a fraction of the Covenant resources, including grogs, can be declared as "personal" (how much is a troupe decision, though we tend to go with the highest request at the table), and divided evenly among the PC magi - obviously, each player gets to assign the build points assigned to his magus as he likes. In the sagas I've played, a fraction of the Covenant resources is almost always "personal" - in several cases all of them.
This neither changes the overall power of the Covenant (obviously, since the total number of resources remains the same), nor creates an imbalance among the magi (since each gets an equal share of the "personal" resources).
It works well in combination with appropriate Hooks such as Factions or Fractured Council, and can be fun if you like inter-PC wheelin' an' dealin'.
In our latest Spring covenant building saga set in the Rhine we had all players bring along 50 BP worth of resources with their magus, plus I think for one Companion already active in play at that time. These resources represent gifts from the magi's parens or resources actually produced for themselves during apprenticeship.
This way we don't start from nothing nor do we just assume some generic resources or buy what seems best. We each decided on some things we thought our magi would have or have received as gift from parens. This was everything from lab texts, vis, books and specialists. And they were donated to the covenant. I've often seen sagas where some magi have favoured covenfolk, servants, specialists, shield grogs or whatever they consider their own, but we've never quantified it.
Objection! My doorman is mine! 
Mind you, he doesn't really have any useful skills and was only a handful of points, so... yeah...
Also, whether a magus has personal property at all beyond the right to sanctum is a covenant decision. Many Spring covenants will expect that everyone's books be available to everyone as needed (subject to the usual dickering and certamen). Similarly, vis is usually divided by covenant rules.
In Springtime, of course, a covenant usually needs everyone involved to be available to pull their weight for the whole, so "personal" simply doesn't mean as much.
What about the tool maker?
I was thinking of him as more of a covenant resource. He just needs to repair my Superior Tools (first).
The Anulus Connectens project has me revisiting a character and tried to age from apprenticeship to archmagus-hood about a year ago. To one up them, I decided to write some fiction and accompany it with stats. Unfortunately, the character would have both personal property and boons and hooks on her character sheet.
(Character went on the first Crusade as a young Maga and became disgusted with it. During the sack of Jerusalem, she took several texts from her Parens and tried to get as far East on the silk road as she could. Her Parens died when a Crusader, antagonized by the Gift, put in arrow in his back in Asia minor the next year. As his only inheritor, this extinguished the claim of deprivation of magical power he had brought against her. Nobody told her about this for about thirty years. Connections with the Suhar, coupled with the Visions flaw and leap of homecoming plus accumulated arcane connections, let her show up when Hermetic Magic got themselves in trouble in the Peria, the Middle East and Africa. She became a bit of a tragic and romantic legend in the Order before showing up again in Europe. The peripheral code of the Levant said, at the time of her Parens death, that the other magi on Crusade get to split the immediate belongings on anyone who dies/goes into final twilight while on Crusade. Several prominent magi in the Levant are more than a bit angry with her for stealing the books that they believe they rightfully should have stolen.)