Expose the beta advisor and memory API tools in Claude Code

### Preflight Checklist

- [x] I have searched [existing requests](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20label%3Aenhancement) and this feature hasn't been requested yet
- [x] This is a single feature request (not multiple features)

### Problem Statement

Please surface the beta API tools advisor_20260301 (advisor tool) and memory_20250818 (memory tool) as configurable tools within Claude Code (CLI + desktop), the way they can already be configured via the Messages API.

Both are standard Claude API tools available to any application that makes API calls, but Claude Code doesn't expose tool configuration, so they can't be used in a Claude Code session today. Two concrete benefits:

Memory tool — Claude Code's auto-memory currently loads only the first ~200 lines / ~25KB of MEMORY.md and silently truncates the rest tail-first at read time (the cap isn't configurable in settings). A directory-backed memory tool (view/create/str_replace/insert/delete/rename over a /memories dir) would remove that single-capped-index limitation entirely — a large memory store navigated without an index that overflows.
Advisor tool — pairing a cheaper executor model with a higher-tier advisor for mid-task strategic guidance is exactly the pattern long-horizon Claude Code coding sessions benefit from, with no way to configure it today.

Ideal: allow enabling these (and other beta API tools) via settings.json tool configuration, with Claude Code handling the beta header.

### Proposed Solution

Ideal: allow enabling these (and other beta API tools) via settings.json tool configuration, with Claude Code handling the beta header.

### Alternative Solutions

_No response_

### Priority

Critical - Blocking my work

### Feature Category

CLI commands and flags

### Use Case Example

_No response_

### Additional Context

_No response_

Start by comparing the existing Messages API tool configuration with Claude Code's settings.json and its CLI and desktop configuration paths. Trace how configurable tools and beta headers are represented. Done means advisor_20260301 and memory_20250818 can be enabled for both surfaces through settings, with their configuration behavior verified.

索引モデルが issue の本文から書いたものです。