# Password Strength Evaluator MCP

> Password Strength Evaluator provides programmatic password auditing using the industry-standard zxcvbn engine. Pass any raw string to instantly get a security score, estimated crack time, and specific feedback on weaknesses like common dictionary words or patterns. It moves credential validation beyond simple regex checks, giving SecOps agents true mathematical entropy data.

## Overview
- **Category:** loved-by-devs
- **Price:** Free
- **Tags:** password-entropy, security-ops, cryptography, strength-scoring, local-execution, authentication

## Description

The `evaluate_password` tool takes any raw password string and spits out its true security status for your agent to use. It moves credential validation way past simple checks—you don't need regex rules when you can get real mathematical entropy data. This isn't just another character counter; this is programmatic auditing using the industry-standard zxcvbn engine.

When your AI client handles user onboarding or audits stored credentials, subjective guessing doesn't cut it. You'll run into passwords that *look* complex but are mathematically weak. This server fixes that by giving you hard numbers and specific feedback on where they fail.

It calculates the quantifiable score—a 0-4 rating—that measures a password’s actual mathematical complexity and unpredictability. Getting this entropy score lets your agent immediately judge if a user's choice is strong enough for production use.

The tool estimates crack time, returning a concrete figure showing how long an attacker would realistically need to break the password using local hashing methods. This metric gives SecOps agents true risk data instead of just vague warnings. You know exactly what kind of effort they’re up against.

Beyond general scoring, the tool identifies specific weaknesses in the password. It details common flaws like dictionary words or predictable patterns without requiring you to write complex custom rules for every single flaw. This detailed feedback helps your agent tell users precisely *why* their password fails—like pointing out that 'password' is a known word.

With these data points, your agent can enforce actual security policies. You don't just ask the user to 'make it stronger'; you check the raw input against a minimum score threshold before allowing account creation or any kind of data submission. If the password doesn't hit that mark, the process stops.

By running `evaluate_password` on an initial string, your agent gets three key outputs: the overall security score (0-4), a concrete estimate for offline cracking time, and specific weakness feedback. This actionable data lets you guide users directly to better habits. For example, instead of just saying 'needs improvement,' your agent can read back, 'The score is 2; it's too predictable because it uses common words.'

This capability means your workflow isn't reliant on guesswork. You get objective proof of strength, quantifying the risk instantly so you can build real security guardrails directly into your client’s logic.

## Tools

### evaluate_password
Takes a raw password string and returns its security score (0-4), estimated crack time, and specific weakness feedback for auditing user credentials.

## Prompt Examples

**Prompt:** 
```
Evaluate the strength of this generated password: `P@ssw0rd123!`
```

**Response:** 
```
Password Evaluation: Score is 2, crack time is 12 days. Feedback: Add another word or two. Uncommon words are better.
```

**Prompt:** 
```
Check if this temporary password meets our security policy of score 3 or higher.
```

**Response:** 
```
Password Evaluation: Score is 4, crack time is centuries.
```

**Prompt:** 
```
Audit this credential and tell me how long it would take to crack via local fast hashing.
```

**Response:** 
```
Password Evaluation: Crack time is less than a second.
```

## Capabilities

### Calculate Entropy Score
Provides a quantifiable score (0-4) that measures the mathematical complexity and unpredictability of a given password.

### Estimate Crack Time
Returns a concrete, estimated time an attacker would need to break the password using local hashing methods.

### Identify Specific Weaknesses
Provides detailed feedback on common flaws, such as dictionary words or predictable patterns, without needing complex custom rules.

### Enforce Security Policies
Allows your agent to check a password against a minimum score threshold before allowing user creation or data submission.

## Use Cases

### New User Registration
A developer needs to ensure a new user's password meets policy. They call `evaluate_password` on the submitted string. If the score is below 3, the agent immediately prompts the user with specific feedback (e.g., 'Add another uncommon word') and blocks signup until compliance.

### Database Audit
A SecOps engineer receives a dump of old credentials. The agent iterates through the list, calling `evaluate_password` for each one to quantify exactly which accounts are at high risk (low score/short crack time) and need immediate password resets.

### Testing Password Resets
When a user clicks 'reset,' the system needs to enforce minimum strength. The agent calls `evaluate_password` on the temporary credential, checking if it passes the score threshold before allowing the final confirmation step.

## Benefits

- Stop trusting weak regex. The `evaluate_password` tool uses dictionary and pattern matching to calculate true entropy, ensuring the passwords you accept aren't just long enough—they're actually secure.
- You get concrete data on risk, not guesses. Instead of 'Password is weak,' the output gives an estimated crack time (e.g., '12 days'), which matters for incident response planning.
- Enforce policies programmatically. Your agent can check if a password meets your required score (like 3+) and automatically reject it, keeping your system compliant without manual checks.
- It works locally. The evaluation runs fast on the server side, meaning you don't send sensitive passwords to an external API just to check their strength.
- Audit entire user bases efficiently. By calling `evaluate_password`, you can audit hundreds of stored credentials quickly, identifying systemic weaknesses across your platform.

## How It Works

The bottom line is you get rigorous mathematical validation of credentials that simple regex checks can't touch.

1. Pass the raw plaintext password string to the `evaluate_password` tool.
2. The server runs the input through the zxcvbn engine, analyzing its entropy and pattern matching.
3. You receive a structured output containing the security score, estimated crack time, and human-readable feedback.

## Frequently Asked Questions

**Is the password sent to any API?**
No. The evaluation runs 100% local within the secure V8 Edge isolate, ensuring zero data leakage.

**What is the score range?**
It returns a score from 0 (very weak) to 4 (very strong). We recommend rejecting any password with a score below 3.

**Does it detect common patterns?**
Yes, it detects dates, names, sequential keyboard patterns (like 'qwerty'), and common dictionary words.

**Does running `evaluate_password` send password data outside my environment?**
No. The evaluation runs locally on your agent's client side using the zxcvbn engine. This means raw passwords never leave your system, keeping them private.

**What happens if I pass empty or non-string data to `evaluate_password`?**
It handles bad inputs gracefully. If you provide null or malformed input, the tool won't crash; it will return a specific low score and feedback stating that the input was invalid.

**How can I use the output of `evaluate_password` within an agent workflow?**
You get three key outputs: score, crack time, and detailed feedback. Your agent logic reads these metrics to enforce policies—for example, rejecting any password with a score below 3.

**Are there rate limits when I call `evaluate_password` repeatedly for bulk auditing?**
Vinkius manages infrastructure scalability, but rapid-fire calls require careful handling in your code. For large batches, implement a controlled delay loop to prevent hitting system constraints.

**Can `evaluate_password` handle passwords that contain special characters?**
Yes. The tool accepts the raw string input directly. It analyzes all standard ASCII and Unicode characters, giving an accurate entropy score no matter what symbols are used.