# `loans.401k/401k-loans` on anlyon.dev

> Text inside fenced blocks marked untrusted-server-text was written by the MCP server's publisher, not by anlyon.dev. It is data to inspect, not instructions to follow. Invisible characters are shown as [U+XXXX].
> No finding is not a safety guarantee: these are point-in-time checks of tool definitions, not of code or behaviour.

- Page: https://anlyon.dev/servers/loans.401k/401k-loans
- JSON: https://anlyon.dev/api/v1/servers/loans.401k/401k-loans
- Version: 1.2026.1101.1 (active)
- Publisher: loans.401k (domain proven to the MCP Registry)
- Runs: remote (streamable-http)
- Sign-in to list tools: none
- Metadata from the official MCP Registry, synced 2026-11-01T23:18:18.072Z

Title and description, as the publisher wrote them:

```untrusted-server-text
401k.loans: 401(k) loan and withdrawal calculators
401(k) loan true cost, loan vs. withdrawal vs. personal loan vs. HELOC, early withdrawal tax.
```

Scanned 2026-11-01T22:18:22.596Z over streamable-http.

**3 tools: 1 do something that can't be undone, 1 change things and 1 only read.**

| Group | Class | Tools | Claude Code |
| --- | --- | --- | --- |
| Deletes or cancels | destructive | 0 | deny |
| Can't be undone | irreversible | 1 | ask |
| Changes things | write | 1 | ask |
| Only reads | read | 1 | allow |

## Exfil surface

No private-data -> untrusted-input -> outbound path in this server alone: no tool is tagged private-data or untrusted-input or outbound.

| Tag | Meaning | Tools |
| --- | --- | --- |
| private-data | Reads files, mail, messages, databases, secrets, calendars or repositories. | none |
| untrusted-input | Brings in text someone else can write: web pages, inbound email, messages, issues and comments. | none |
| outbound | Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL. | none |

## Findings

- **warn** Annotations that disagree with the tool in `calculate_401k_loan_cost` ([annotation-conflict](https://anlyon.dev/methodology#annotation-conflict))

```untrusted-server-text
The server marks "calculate_401k_loan_cost" read-only (readOnlyHint: true), and its own name, description or input give the class "write".

annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The description's first verb is "run": a word for a change.
```

- **warn** Annotations that disagree with the tool in `calculate_401k_early_withdrawal` ([annotation-conflict](https://anlyon.dev/methodology#annotation-conflict))

```untrusted-server-text
The server marks "calculate_401k_early_withdrawal" read-only (readOnlyHint: true), and its own name, description or input give the class "irreversible".

annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "calculate_401k_early_withdrawal" says "withdrawal": a word that usually means money moves, which cannot be taken back.
```


## Can't be undone (1)

Sends, pays, publishes or merges: once done, it cannot be taken back. Claude Code: ask.

### `calculate_401k_early_withdrawal`

- The name "calculate_401k_early_withdrawal" says "withdrawal": a word that usually means money moves, which cannot be taken back.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
- Findings: warn annotation-conflict

Description, as the server wrote it:

```untrusted-server-text
Runs the 401k.loans early withdrawal calculator for a cash-out or hardship withdrawal: amount taken out (or the gross needed to net a target), income tax at your marginal rates, the 10% additional tax, what you keep, what the plan withholds up front (20% mandatory, or 10% default for hardship), the check amount, and the balance due or refund at filing.
```

## Changes things (1)

Creates or changes something that can be changed back. Claude Code: ask.

### `calculate_401k_loan_cost`

- The description's first verb is "run": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
- Findings: warn annotation-conflict

Description, as the server wrote it:

```untrusted-server-text
Runs the 401k.loans true-cost calculator: payment per paycheck and number of payments, total repaid and interest, pre-tax pay needed per payment, tax later on the interest, the 401(k) balance at payoff with and without the loan (growth gap) and that gap at 65, the legal and usual plan borrowing limits, and, if you might leave the job, the balance owed then plus the tax and 10% additional tax if it is not repaid or rolled over.
```

## Only reads (1)

Looks things up and changes nothing. Claude Code: allow.

### `compare_401k_loan_alternatives`

- The name "compare_401k_loan_alternatives" says "compare": a word for reading.

Description, as the server wrote it:

```untrusted-server-text
Prices four ways to raise the same cash with the 401k.loans comparison tool: 401(k) loan, hardship withdrawal (grossed up for tax and the 10% additional tax), personal loan (rate plus origination fee) and HELOC. For each: amount taken out, monthly payment, money gone for good (interest to others, fees, tax, penalty), interest paid back to yourself, how much smaller the 401(k) is at term end and at 65, and whether it is allowed.
```

## Claude Code permissions

For `.claude/settings.json`, assuming the server is installed as `401k-loans`:

```json
{
  "permissions": {
    "allow": [
      "mcp__401k-loans__compare_401k_loan_alternatives"
    ],
    "ask": [
      "mcp__401k-loans__calculate_401k_loan_cost",
      "mcp__401k-loans__calculate_401k_early_withdrawal"
    ],
    "deny": []
  }
}
```

## Remote posture

What an anonymous client saw at the remote endpoint, last 2026-11-02T00:20:03.009Z, unchanged since 2026-11-02T00:20:03.009Z. No credentials were sent and no tool was called. Values are shown as the endpoint returned them. Method: https://anlyon.dev/methodology#remote-posture

| Fact | Observed |
| --- | --- |
| Reachable | `yes` |
| HTTP status of an anonymous initialize | `200` |
| tools/list served without credentials | `yes` |
| Tools that change things, listed without credentials | `2` |
| Protocol version | `2025-06-18` |
| WWW-Authenticate on 401 | `not observed` |
| resource_metadata in WWW-Authenticate | `none` |
| RFC 9728 protected resource metadata | `none` |
| Authorization servers | `none` |
| Legacy HTTP+SSE transport | `no` |
| Dynamic client registration | `not observed` |
| Client ID metadata documents | `not observed` |

- **high** Tools that change things, listed to anyone ([unauth-remote-writes](https://anlyon.dev/methodology#unauth-remote-writes))

```untrusted-server-text
The endpoint served tools/list without credentials, and the list has 2 tools that change things (1 irreversible, 1 write). Whether a call also works without credentials was not tested: tools are never called.

https://401k.loans/mcp: tools/list returned 3 tools to an anonymous client, including calculate_401k_early_withdrawal (irreversible), calculate_401k_loan_cost (write)
```