# loginWithId

Authenticates a user to FusionAuth. This API optionally requires an API key. See <code>Application.loginConfiguration.requireAuthentication</code>.

Agent View of the PolicyLayer registry record for `loginWithId`. HTML page: https://policylayer.com/tools/io-fusionauth-mcp-api/loginwithid

## Facts

- Tool: `loginWithId`
- Server: Fusionauth (`@fusionauth/mcp-api`) — https://policylayer.com/tools/io-fusionauth-mcp-api.md
- Install: `npx -y @fusionauth/mcp-api`
- Homepage: https://github.com/FusionAuth/fusionauth-mcp-api
- Risk category: Execute (High 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": "loginWithId",
    "arguments": {}
  }
}
```

## Why loginWithId is rated High

Authenticating a user is not a simple read or write; it executes an authentication flow that produces tokens, sessions, and audit events in FusionAuth. Misuse could allow an AI agent to authenticate as arbitrary users, potentially bypassing access controls. The optional API key requirement lowers the barrier for misuse in some configurations.

From the tool's own definition: "'Authenticates a user to FusionAuth' — triggers an external authentication operation with session/token side effects"

## Use case

AI agents invoke loginWithId to trigger actions in Fusionauth. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "loginWithId": {
      "limits": [
        {
          "counter": "loginwithid_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Fusionauth (313)

- `deleteAPIKeyWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteapikeywithid.md
- `deleteApplicationRoleWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteapplicationrolewithid.md
- `deleteApplicationWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteapplicationwithid.md
- `deleteConnectorWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteconnectorwithid.md
- `deleteConsentWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteconsentwithid.md
- `deleteEmailTemplateWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteemailtemplatewithid.md
- `deleteEntityGrantWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteentitygrantwithid.md
- `deleteEntityTypePermissionWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteentitytypepermissionwithid.md
- `deleteEntityTypeWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteentitytypewithid.md
- `deleteEntityWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteentitywithid.md
- `deleteFormFieldWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteformfieldwithid.md
- `deleteFormWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteformwithid.md
- `deleteGroupMembersWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletegroupmemberswithid.md
- `deleteGroupWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletegroupwithid.md
- `deleteIdentityProviderWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteidentityproviderwithid.md
- `deleteIPAccessControlListWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteipaccesscontrollistwithid.md
- `deleteJwtRefresh` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletejwtrefresh.md
- `deleteKeyWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletekeywithid.md
- `deleteLambdaWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletelambdawithid.md
- `deleteMessageTemplateWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletemessagetemplatewithid.md
- `deleteMessengerWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletemessengerwithid.md
- `deleteOAuthScopeWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteoauthscopewithid.md
- `deleteTenantWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletetenantwithid.md
- `deleteThemeWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deletethemewithid.md
- `deleteUserActionReasonWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteuseractionreasonwithid.md
- `deleteUserActionWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteuseractionwithid.md
- `deleteUserBulk` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteuserbulk.md
- `deleteUserLinkWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteuserlinkwithid.md
- `deleteUserRegistrationWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteuserregistrationwithid.md
- `deleteUserTwoFactorWithId` — Destructive — https://policylayer.com/tools/io-fusionauth-mcp-api/deleteusertwofactorwithid.md
- …and 283 more: https://policylayer.com/tools/io-fusionauth-mcp-api.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=io-fusionauth-mcp-api · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-fusionauth-mcp-api