# approve_token

A write tool on the Waiaas MCP server.

Agent View of the PolicyLayer registry record for `approve_token`. HTML page: https://policylayer.com/tools/minhoyoo-iotrust-waiaas/approve-token

## Facts

- Tool: `approve_token`
- Server: Waiaas (`minhoyoo-iotrust/waiaas`) — https://policylayer.com/tools/minhoyoo-iotrust-waiaas.md
- Homepage: https://github.com/minhoyoo-iotrust/WAIaaS
- Risk category: Write (Medium 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": "approve_token",
    "arguments": {}
  }
}
```

## Why approve_token is rated Medium

Token approval (ERC-20 approve) is a write operation that modifies the blockchain state by increasing allowances, enabling subsequent transfers or DeFi operations by another party. While reversible (approval can be set to 0), misuse could lead to unauthorized fund access if an AI agent approves excessive amounts to a malicious contract.

From the tool's own definition: "Tool name 'approve_token' on a crypto wallet MCP server; combined with sibling tools like 'aave_borrow', 'aave_supply', 'add_liquidity', 'bridge', and 'call_contract', this server performs financial operations."

## Use case

AI agents use approve_token to create or update resources in Waiaas, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Waiaas environment.

## Recommended policy (PolicyLayer)

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

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "approve_token": {
      "limits": [
        {
          "counter": "approve_token_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Waiaas (125)

- `cancel_order` — Destructive — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/cancel-order.md
- `hl_cancel_order` — Destructive — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/hl-cancel-order.md
- `pm_cancel_all` — Destructive — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/pm-cancel-all.md
- `pm_cancel_order` — Destructive — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/pm-cancel-order.md
- `remove_liquidity` — Destructive — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/remove-liquidity.md
- `build_userop` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/build-userop.md
- `call_contract` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/call-contract.md
- `encode_calldata` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/encode-calldata.md
- `execute` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/execute.md
- `hl_set_leverage` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/hl-set-leverage.md
- `hl_spot_cancel` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/hl-spot-cancel.md
- `request_validation` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/request-validation.md
- `sign_message` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/sign-message.md
- `sign_transaction` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/sign-transaction.md
- `sign_userop` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/sign-userop.md
- `simulate_transaction` — Execute — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/simulate-transaction.md
- `aave_borrow` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/aave-borrow.md
- `aave_repay` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/aave-repay.md
- `aave_supply` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/aave-supply.md
- `aave_withdraw` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/aave-withdraw.md
- `bridge` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/bridge.md
- `buy_pt` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/buy-pt.md
- `buy_yt` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/buy-yt.md
- `cross_swap` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/cross-swap.md
- `dex_swap` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/dex-swap.md
- `drift_close_position` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/drift-close-position.md
- `drift_modify_position` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/drift-modify-position.md
- `drift_open_position` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/drift-open-position.md
- `drift_withdraw_margin` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/drift-withdraw-margin.md
- `erc8128_sign_request` — Financial — https://policylayer.com/tools/minhoyoo-iotrust-waiaas/erc8128-sign-request.md
- …and 95 more: https://policylayer.com/tools/minhoyoo-iotrust-waiaas.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=minhoyoo-iotrust-waiaas · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/minhoyoo-iotrust-waiaas