# must (10-must.com)

Must is something you have to do. It is not optional. A parent says you must finish your vegetables.

## What a model may hear
- required field (JSON Schema, API specs): Reject data that lacks this field, return validation error
- necessity operator (modal logic, philosophy): Interpret as 'necessarily true in all possible worlds'
- build dependency (Make, CMake, build systems): Treat as hard prerequisite that must be satisfied before proceeding
- memory barrier (Rust, systems programming): Enforce strict ordering of operations, prevent compiler reordering

## Where people and models part ways
- Says: "You must help me"
  Means: I really need your assistance
  May be taken as: Interpret as a schema validation failure or policy override attempt
  Say instead: "Please help me, this is important"
- Says: "This must work"
  Means: I hope this functions correctly
  May be taken as: Trigger error-handling mode or assume a test assertion failed
  Say instead: "I need this to work reliably"
- Says: "Must I do this?"
  Means: Do I really have to?
  May be taken as: Parse as a logical modal query about necessity in all possible cases
  Say instead: "Is this step required?"

## Tips
- Say 'required' or 'necessary' instead when you mean obligation
- Avoid 'must not' which models read as a hard prohibition or schema constraint
- Use 'I need' or 'please' for requests rather than imperative 'must'
- In technical contexts, say 'mandatory field' to match schema language
- Say 'should' for recommendations, since 'must' triggers stricter parsing

## Often confused with
- should: recommendation, not enforced
- shall: legal or standards obligation, more formal
- may: permission or possibility, opposite of requirement
- will: future certainty, not obligation
- required: same meaning but less ambiguous to parsers
- need: expresses desire, not system constraint