# throw-custom-error

Throws a custom PublicMcpError with specified code and message

Agent View of the PolicyLayer registry record for `throw-custom-error`. HTML page: https://policylayer.com/tools/frontmcp/throw-custom-error

## Facts

- Tool: `throw-custom-error`
- Server: Frontmcp (`agentfront/frontmcp`) — https://policylayer.com/tools/frontmcp.md
- Homepage: https://github.com/agentfront/frontmcp
- Risk category: Other (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

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

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "throw-custom-error",
    "arguments": {}
  }
}
```

## Why throw-custom-error is rated Low

This tool throws a custom error object, which is a testing/diagnostic utility that produces an error condition within the MCP framework. It does not read, write, execute external code, delete data, or involve finances. It simulates or triggers an error response, which is essentially a no-op in terms of side effects on external systems — it likely exists for testing error handling behavior.

From the tool's own definition: "'Throws a custom PublicMcpError with specified code and message'"

## Use case

AI agents call throw-custom-error as a supporting operation in Frontmcp workflows.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "throw-custom-error": {
      "limits": [
        {
          "counter": "throw-custom-error_rate",
          "window": "minute",
          "max": 60,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Frontmcp (205)

- `clear-audit-log` — Destructive — https://policylayer.com/tools/frontmcp/clear-audit-log.md
- `clear-replay-buffer` — Destructive — https://policylayer.com/tools/frontmcp/clear-replay-buffer.md
- `clear-session-notifications` — Destructive — https://policylayer.com/tools/frontmcp/clear-session-notifications.md
- `crm-reset` — Destructive — https://policylayer.com/tools/frontmcp/crm-reset.md
- `delete-vault-entry` — Destructive — https://policylayer.com/tools/frontmcp/delete-vault-entry.md
- `notes-reset` — Destructive — https://policylayer.com/tools/frontmcp/notes-reset.md
- `remove_job` — Destructive — https://policylayer.com/tools/frontmcp/remove-job.md
- `remove_workflow` — Destructive — https://policylayer.com/tools/frontmcp/remove-workflow.md
- `reset-stats` — Destructive — https://policylayer.com/tools/frontmcp/reset-stats.md
- `secret` — Destructive — https://policylayer.com/tools/frontmcp/secret.md
- `users-delete` — Destructive — https://policylayer.com/tools/frontmcp/users-delete.md
- `admin_action` — Execute — https://policylayer.com/tools/frontmcp/admin-action.md
- `admin-background-job` — Execute — https://policylayer.com/tools/frontmcp/admin-background-job.md
- `admin-only` — Execute — https://policylayer.com/tools/frontmcp/admin-only.md
- `browser_test` — Execute — https://policylayer.com/tools/frontmcp/browser-test.md
- `build-shell` — Execute — https://policylayer.com/tools/frontmcp/build-shell.md
- `cancellable-wait` — Execute — https://policylayer.com/tools/frontmcp/cancellable-wait.md
- `cold-start-test` — Execute — https://policylayer.com/tools/frontmcp/cold-start-test.md
- `concurrency-mutex` — Execute — https://policylayer.com/tools/frontmcp/concurrency-mutex.md
- `concurrency-queued` — Execute — https://policylayer.com/tools/frontmcp/concurrency-queued.md
- `deploy_application` — Execute — https://policylayer.com/tools/frontmcp/deploy-application.md
- `emit-app-event` — Execute — https://policylayer.com/tools/frontmcp/emit-app-event.md
- `execute_job` — Execute — https://policylayer.com/tools/frontmcp/execute-job.md
- `execute_workflow` — Execute — https://policylayer.com/tools/frontmcp/execute-workflow.md
- `expensive-operation` — Execute — https://policylayer.com/tools/frontmcp/expensive-operation.md
- `experimental-agent` — Execute — https://policylayer.com/tools/frontmcp/experimental-agent.md
- `gated-acme` — Execute — https://policylayer.com/tools/frontmcp/gated-acme.md
- `load-component` — Execute — https://policylayer.com/tools/frontmcp/load-component.md
- `long-running-task` — Execute — https://policylayer.com/tools/frontmcp/long-running-task.md
- `node_runtime_tool` — Execute — https://policylayer.com/tools/frontmcp/node-runtime-tool.md
- …and 175 more: https://policylayer.com/tools/frontmcp.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`

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