Does Read Magic tell you what a written spell does?

[Ultrace]

A question has come up regarding a game I run, which I've never considered before. There are dozens and dozens (hundreds?) of spells out there.

Do spellcasters "know" what every spell does, even those outside their magical sphere? Read Magic allows you to decipher a scroll, which would include what spell is contained on it. But apart from, say, the spell's name, what does it tell you about the spell itself? Does deciphering the scroll impart knowledge of whether it's divine or arcane? What classes can use it? Details about the spell's range, effects, and so on?

I didn't see anything about this in Spellcraft, Read Magic or Scrolls. They explain how you can determine what spells are on a scroll, but does anyone know where the Spellcraft check to understand what a spell actually does is?

[DungeonmasterCal]

I allow them to be able to read the spell without speaking it out loud. If they do that, however, all bets are off. This may be more RAI than RAW.

[dragonhunterq]

If you know what the spell is you know what it does.
Anything else is an ugly can of "GM Gotcha" that is best left closed.

[OmniMage]

Arcane Magical Writings, p. 218-219 of the core rulebook

Quote:

Once a character deciphers a particular piece of

magical writing, he does not need to decipher it again.
Deciphering magical writing allows the reader to identify
the spell and gives some idea of its effects (as explained
in the spell description). If the magical writing is a scroll
and the reader can cast arcane spells, he can attempt to
use the scroll.

So yes, a read magic spell will allow you to know what kind of spell they are reading and general idea of what it does.

[blahpers]

"Surprise, you actually prepared a specially researched detonate that just happened to be called cure light wounds! Sucker!"

...Ehh, how about no.

You know everything in the spell description.