# Code Review — Step 4: `Requirement` enum

## Verdict

APPROVE

## Findings

No blocking findings.

The Step 4 implementation is narrowly scoped and preserves the existing behavior:

- `Requirement` remains a typed string enum with the existing wire values (`"read"`, `"write"`, `"delete"`).
- The zero-value/default-read behavior is centralized in `Requirement.effective()` and used by `RequiresWrite`, `RequiresDelete`, and `icuvisor_list_advanced_capabilities` serialization.
- The `list_advanced_capabilities` `requirement` field still emits `"read"` for tools that omit `Requirement`, preserving the serialized catalog behavior.
- I did not find remaining raw empty-string requirement comparisons in `internal/`.

## Verification

- Reviewed `git diff 59516cf4f8a60724e32c93c72699b26222c22930..HEAD --name-only` and the full diff.
- Read the task prompt, status, and changed tool files for context.
- Ran `go test ./internal/tools ./internal/mcp ./internal/safety` successfully.
- Ran `go test ./internal/toolchecks` successfully.
- Ran `git diff --check 59516cf4f8a60724e32c93c72699b26222c22930..HEAD` successfully.
- Ran a targeted grep for raw `Requirement == ""` / `Requirement != ""` comparisons; none remain.
