# Uuid inspect

`uuid-inspect` · version 1.0.0 · Identifiers & check digits · free, no key needed

Validate a canonical UUID and report its lowercase value, variant, version, and nil status.

**Use when you need to: inspect a UUID · validate canonical UUID · normalize UUID to lowercase.**

## Decide before calling

Read the [versioned contract](/v1/tools/uuid-inspect/versions/1.0.0) and the supported scope below. Reuse `uuid-inspect@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `uuid-inspect@1.0.0` for inspect a UUID. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- inspect a UUID
- validate canonical UUID
- normalize UUID to lowercase
- find UUID version
- identify UUID variant
- check whether UUID is nil
- parse UUID URN
- report UUID metadata

## Not supported

- generate a UUID
- validate version-specific timestamps or field semantics
- accept braces, hyphenless UUIDs, whitespace, or Unicode lookalikes

## Behavior

- Accept exactly 8-4-4-4-12 ASCII hexadecimal text, optionally preceded by the exact lowercase urn:uuid: prefix; hexadecimal digits are case-insensitive.
- Valid input is returned without the optional prefix and with hexadecimal digits lowercased.
- Version is the numeric third-group high nibble (0 through 15); this does not validate version-specific timestamp or field semantics.
- Variant follows the fourth-group high bits: 0xxx ncs, 10xx rfc_9562, 110x microsoft, or 111x future.
- Nil is true only for 128 zero bits; nil still has bit-derived ncs variant and version 0.
- Well-typed in-limit noncanonical text returns valid false and null metadata; no trimming, generation, trust, uniqueness, or security claim is made.
- Input over 45 UTF-8 bytes throws limit_exceeded before grammar matching.

## Input

- `value` (string, required): min length 1; max length 45

## Output

- `valid` (boolean, required)
- `normalized` (string or null, required)
- `variant` (one of "ncs", "rfc_9562", "microsoft", "future", null, required)
- `version` (integer or null, required): min 0; max 15
- `nil` (boolean, required)
- `reason` (one of "not_canonical_uuid", null, required)

## Limits

- max input bytes: 45

## Example

Request input:

```json
{
  "value": "urn:uuid:550E8400-E29B-41D4-A716-446655440000"
}
```

Response:

```json
{
  "result": {
    "valid": true,
    "normalized": "550e8400-e29b-41d4-a716-446655440000",
    "variant": "rfc_9562",
    "version": 4,
    "nil": false,
    "reason": null
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "uuid-inspect",
  "version": "1.0.0",
  "input": {
    "value": "urn:uuid:550E8400-E29B-41D4-A716-446655440000"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/uuid-inspect/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"value":"urn:uuid:550E8400-E29B-41D4-A716-446655440000"}'
```

The machine-readable contract is at [/v1/tools/uuid-inspect/versions/1.0.0](/v1/tools/uuid-inspect/versions/1.0.0).

### CLI

```sh
node cli.mjs run uuid-inspect 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

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