Use CLAUDE.md for stable, human-written project instructions; Claude Code auto memory for useful preferences and corrections Claude has learned; and a memory MCP or API tool when an application needs an explicit way to read and write external memory. They serve different jobs. None of them, by itself, guarantees that Claude will follow a rule or that a fact will be saved and retrieved.
What each option is for
CLAUDE.md: project instructions you maintain
In Claude Code, CLAUDE.md is a plain Markdown file for durable instructions, project conventions, and recurring workflows. Put information there when you want to author and review it yourself and have it guide relevant sessions. Examples include build and test commands, coding conventions, architectural constraints, and corrections that should routinely apply. Anthropic describes the file as something Claude Code reads automatically at session start within its scope; subdirectory files are loaded as Claude works in those directories. See the Claude Code best practices.
![Claude AI for Beginners Bible: [5 in 1] The Ultimate Guide to Automate Your Work, Save Hours Every Week, and Use AI for Real-World Results](https://m.media-amazon.com/images/I/415+fSJacsL._SL160_.jpg)
As an Amazon Associate I earn from qualifying purchases.
Keep the file focused and review it for stale guidance. A rule that no longer reflects the project can be counterproductive, and a long file can make the important instructions harder to find.
Recommended Free Tools
Auto memory: notes Claude Code maintains
Claude Code auto memory is separate from CLAUDE.md. Claude writes notes about useful learned preferences, corrections, and project context. Its MEMORY.md index is loaded into each session, while topic-specific files can be read when relevant. It is intended for information Claude learned that cannot simply be derived from the code. Anthropic explains the feature in How Claude remembers your project.
#1 Best Overall
That makes auto memory a fit for recurring feedback you want Claude Code to retain without manually turning every observation into project documentation. It is not a substitute for a reviewed, authoritative project rule: you do not maintain its notes in the same way you maintain CLAUDE.md.
Memory MCP or API tool: an integration with storage behind it
A memory MCP server exposes a tool interface Claude can use to retrieve or update information. MCP is the connection protocol, not a promise about what the server stores, how it searches, or how long it retains data. Those capabilities depend on the server and its configuration. The MCP overview explains what MCP is.
Rank #2
Anthropic’s API memory tool similarly lets Claude request operations on a memory directory, but the application must implement the handler and provide the storage. That storage might be local files, a database, cloud storage, or encrypted files. The API tool documentation describes the application-side responsibilities at Memory tool.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallOutdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchHow to choose where a fact belongs
| Question | Best fit | Why |
|---|---|---|
| Is this a stable convention or instruction that a person should define for relevant project sessions? | CLAUDE.md |
It is human-maintained project guidance loaded in scope. |
| Is this a preference or correction Claude learned and should retain across sessions? | Auto memory | It is Claude-maintained learning, organized per repository. |
| Must Claude explicitly look up or update a larger, shared, searchable, or application-owned store? | Memory MCP or API tool | The integration provides a read/write interface; the server or application determines storage and retrieval behavior. |
| Must an invalid action be stopped regardless of what Claude decides? | An enforcement control, such as a hook | Instructions and memory provide context; they do not enforce a prohibition. |
A useful distinction is who should own the information. Put reviewed project policy in the file people maintain. Let auto memory retain learned context where that is useful. Use an external memory integration when you need a defined application or server to manage retrieval and writes.
Context is not enforcement
Claude Code documentation says CLAUDE.md and auto memory are context, not enforced configuration: “Both are loaded at the start of every conversation. Claude treats them as context, not enforced configuration.” A note can inform a response, but it cannot guarantee that Claude complies. If a requirement must block an action, use a control designed to gate that action, such as a PreToolUse hook, rather than relying on a sentence in a file or memory.
Setting up a memory MCP in Claude Code
Configuration depends on the server and Claude Code release. The Claude Code MCP FAQ describes adding a server with claude mcp add or configuring one in a project-level .mcp.json. After setup, restart Claude Code and run /mcp to check the connection. The connection check confirms that the server is available; it does not establish that the server’s memory is persistent or that its retrieval policy suits your needs. See the Claude Code MCP guide.
Responsibilities when using the API memory tool
With the API memory tool, the application processes Claude’s requested operations and returns tool results. Anthropic assigns file-operation safeguards to the application, not to an automatically supplied storage backend. Before using it, the application should:
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitches- Validate paths and resolve canonical paths before operating on files.
- Prevent path traversal outside the intended memory root.
- Set appropriate size limits and expiration rules.
- Decide how sensitive data is handled and protected.
- Choose and operate the storage backend, such as files or a database.
These are application responsibilities because a tool interface alone does not secure or govern the underlying memory store.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
