# hash

Computes cryptographic digests and HMAC signatures. Returns hex and base64 at once, so a webhook signature can be compared in whichever encoding the provider uses. MD5 and CRC32 are included for checksums and legacy fixtures; they are not secure for authentication.

Agent View of the PolicyLayer registry record for `hash`. HTML page: https://policylayer.com/tools/com-fluentedi-tools/hash

## Facts

- Tool: `hash`
- Server: Tools (`https://fluentedi.com/mcp`) — https://policylayer.com/tools/com-fluentedi-tools.md
- Homepage: https://github.com/https://fluentedi.com/mcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server CORS policy: *
- Server rate-limited: no
- Parameters: 4 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `input` | string | yes | Text to hash. |
| `hmac_key` | string | no | When set, computes HMAC-<algorithm> with this key instead of a plain digest. Not supported for md5/crc32. |
| `algorithms` | array | no | Any of: md5, sha1, sha256, sha384, sha512, crc32. |
| `input_encoding` | string | no | How to read `input` into bytes. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "hash",
    "arguments": {
      "input": "<input>"
    }
  }
}
```

## Why hash is rated Low

Even though hash only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

## Use case

AI agents call hash to retrieve information from Tools without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Tools:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "hash": {}
  }
}
```

## Other tools on Tools (16)

- `cron_next` — Execute — https://policylayer.com/tools/com-fluentedi-tools/cron-next.md
- `edi_build` — Execute — https://policylayer.com/tools/com-fluentedi-tools/edi-build.md
- `edi_parse` — Execute — https://policylayer.com/tools/com-fluentedi-tools/edi-parse.md
- `edi_validate` — Read — https://policylayer.com/tools/com-fluentedi-tools/edi-validate.md
- `http_assert` — Read — https://policylayer.com/tools/com-fluentedi-tools/http-assert.md
- `http_check` — Read — https://policylayer.com/tools/com-fluentedi-tools/http-check.md
- `json_query` — Read — https://policylayer.com/tools/com-fluentedi-tools/json-query.md
- `json_repair` — Read — https://policylayer.com/tools/com-fluentedi-tools/json-repair.md
- `math_eval` — Read — https://policylayer.com/tools/com-fluentedi-tools/math-eval.md
- `time_diff` — Read — https://policylayer.com/tools/com-fluentedi-tools/time-diff.md
- `time_now` — Read — https://policylayer.com/tools/com-fluentedi-tools/time-now.md
- `time_window` — Read — https://policylayer.com/tools/com-fluentedi-tools/time-window.md
- `tool_describe` — Read — https://policylayer.com/tools/com-fluentedi-tools/tool-describe.md
- `tool_search` — Read — https://policylayer.com/tools/com-fluentedi-tools/tool-search.md
- `time_convert` — Write — https://policylayer.com/tools/com-fluentedi-tools/time-convert.md
- `tool_call` — Write — https://policylayer.com/tools/com-fluentedi-tools/tool-call.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-fluentedi-tools · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-fluentedi-tools