I would like to make a better version of the DnDBeyond spell search tool (mainly so I do not need to overcomplicate this answer), but I would like to know if abiding by a layman's reading of the 'Fan Content Policy' would be sufficient to do so?
The gist of the policy is:
In short, your use of Wizards’ IP in your Fan Content is governed by the same rules you learned on the playground: share freely, keep it clean, and don’t hurt others.
And then lists in plain English (i.e. not legalese) some points to abide by.
The policy is fairly simple, but I want to be certain that my intended use case doesn't fall foul of this policy (say, some spells are some how excluded), or others I haven't seen, without involving lawyers or other paid legal services.
The only potential issue is that I intend to allow filtering and sorting over information extracted from text.
Although my understanding of the policy is that my intended 'content', I'm seeking advice about it, hopefully people who have used it or been involved in its use before. I'm strictly not seeking legal advice.
Best Answer
The Fan Content Policy is the same thing that enables the fan-made Magic card search engine Scryfall to operate. I've been active in Scryfall's community nearly since the time it was launched: they get along with Wizards of the Coast, whose staff have been using it on the public record as staff members for years. I've never heard of them having to remove features or content. They extensively record Wizards's IP, filter it, and sort it in loads of different ways.
You'll see them mention this explicitly in their footer:
Safe to say the Fan Content Policy is basically fine with you making a detailed search of publicly available D&D content. Naturally you still have to abide by other restrictions, including that the search engine and its content must be free to use with no paywalls at any point.
That said, you wouldn't be able to just reproduce everything from inside the books, since that'd be damaging to Wizards's IP. We know, however, that you are permitted to use the D&D 5e SRD under the OGL and produce content shared by that. This is the license that let Paizo take D&D 3.5e and create and sell Pathfinder—you can make a search engine with this license.
Scryfall's allowed to archive the data of every single Magic card that exists because knowing about the Magic cards doesn't let you play Magic—you still have to buy the physical cards themselves. But that same principle doesn't apply to D&D game content.
In summary: