As we’re in the infancy of this tech, and things change very quickly, have in mind I’m writting this on October 2026, and things might change drastically in the future.

Understanding configuration levels

Claude has 3 levels worth mentioning

1. Enterprise-level: This is the highest level and the one we have the least control. This is meant for your organization to push rules/restrictions to your harness. If you use Claude outside an organization (just for yourself), you can disregard this.
2. User-level: These are configurations that rule all projects in our machine.
3. Project-level: Rules that affect only the session started from that specific folder/workspace.

Deterministic vs non-deterministic rules and constrains

There are reasons why we would add rules or constraints in different places.

CLAUDE.MD

Claude’s main entry point. This file will always be read first, loaded into the context and, most of the time, be the main set of instructions.

ANYWAYS… rules like “don’t use X tool” or “never execute Y” are honestly a hit and miss. Many times I got to remind Claude to stop doing something I added in my user level CLAUDE.MD just to get the classic “oh right, sorry, I missed that, it won’t happen again”. Hooks are the way to go for those cases.

Keep more broad, less important information here, like “response style” or “verbostity level” because CLAUDE.MD is non-deterministic. ¹

Also, keep this file as short as possible because this is information that is loaded in the “context”, that context is finite and we need it. Even though Anthropic doesn’t provide a specific number, general consensus is less that 200 lines is good, less than 60 ideal. ²

Hooks

On the other side, hooks are determinisitic ³. Just like git hooks, these will always be executed upon certain events.

Based on below categories, the events are:

And based on those events there’s supports for multiple handler types (per documentation ⁴):

There’s no need to memorize anything here, but understanding different levels, and the capabilities and limitations that exist gives us a great advantage at getting good results. That should be enough to know when to ask our agent to add a hook or a rule, and at what level depending our workflow.