# prepare_token_approve Build an unsigned approve(spender, amount) transaction that raises (or sets) an ERC-20 allowance — the structured inverse of prepare_revoke_approval. amount is a decimal in token units (e.g. "10" for 10 USDC) or the literal "max" for unlimited. Refuses unlimited approvals to canonical no-key addresses (0x0…0, 0x0…dEaD, 0xdEaD…0, 0xff…ff) with BURN_ADDRESS_UNLIMITED_APPROVAL; override via acknowledgeBurnApproval: true only when the user explicitly asked for that exact spender + unlimited amount. Resolves a friendly spender label from the canonical CONTRACTS table so the description + Ledger preview reads as "Approve USDC for Aave V3 Pool, 1000 USDC" rather than a raw hex address. EVM-only. Prefer protocol-specific prepare_* (e.g. prepare_aave_supply) when the approval is bundled with a downstream action — those route through the shared buildApprovalTx helper which handles the USDT-style reset pattern in one step. Use this tool for one-off allowance-setting that doesn't fit a bundled prepare. Agent View of the PolicyLayer registry record for `prepare_token_approve`. HTML page: https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-token-approve ## Facts - Tool: `prepare_token_approve` - Server: VaultPilot MCP (`vaultpilot-mcp`) — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp.md - Install: `npx -y vaultpilot-mcp` - Homepage: https://github.com/szhygulin/vaultpilot-mcp - Risk category: Write (Medium risk) - Registry record: grade F, identity unverified - Server rate-limited: no - Parameters: 6 (4 required) - Recommended policy verdict: Rate-limited ## Parameters | Parameter | Type | Required | Description | | --- | --- | --- | --- | | `chain` | string | no | | | `token` | string | yes | ERC-20 contract address. Must be the actual token contract — wrappers and aTokens have their own approval surfaces and aren't supported here. | | `amount` | string | yes | Decimal amount in token units, NOT raw wei/base units. Example: "10" for 10 USDC. Decimals resolved from the token contract. Pass "max" for the uint256-max unli | | `wallet` | string | yes | EVM wallet that grants the allowance. Must be paired via `pair_ledger_live`. | | `spender` | string | yes | Address that will be allowed to pull tokens via `transferFrom`. Typically a protocol contract (Aave V3 Pool, Uniswap SwapRouter, etc.) or any EOA. Use the read- | | `acknowledgeBurnApproval` | boolean | no | Override flag for the BURN_ADDRESS_UNLIMITED_APPROVAL refusal. Required only when `amount` is `max` AND `spender` is a canonical no-key address (`0x0…0`, `0x0…d | 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": "prepare_token_approve", "arguments": { "token": "", "amount": "", "wallet": "", "spender": "" } } } ``` ## Why prepare_token_approve is rated Medium This is Write category because it creates/modifies token allowances reversibly via `approve()`. It is not Execute because the tool itself does not spend tokens or trigger transfers — it only *prepares* an unsigned transaction that delegates permission to a spender. From the tool's own definition: "Tool builds an unsigned ERC-20 `approve(spender, amount)` transaction that 'raises (or sets) an allowance' — a reversible modification of token permissions." Risk signals: Handles credentials or secrets (token) ## Use case AI agents use prepare_token_approve to create or update resources in VaultPilot MCP, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your VaultPilot MCP environment. ## Recommended policy (PolicyLayer) Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches VaultPilot MCP: ```json { "version": "1", "default": "deny", "tools": { "prepare_token_approve": { "limits": [ { "counter": "prepare_token_approve_rate", "window": "minute", "max": 30, "scope": "grant" } ] } } } ``` ## Other tools on VaultPilot MCP (188) - `prepare_btc_lifi_swap` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-btc-lifi-swap.md - `prepare_btc_rbf_bump` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-btc-rbf-bump.md - `prepare_jito_stake` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-jito-stake.md - `prepare_marginfi_init` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-marginfi-init.md - `prepare_solana_nonce_close` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-solana-nonce-close.md - `prepare_sunswap_swap` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-sunswap-swap.md - `prepare_uniswap_v3_burn` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-uniswap-v3-burn.md - `prepare_uniswap_v3_mint` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-uniswap-v3-mint.md - `remove_contact` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/remove-contact.md - `unregister_btc_multisig_wallet` — Destructive — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/unregister-btc-multisig-wallet.md - `combine_btc_psbts` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/combine-btc-psbts.md - `pair_ledger_btc` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/pair-ledger-btc.md - `prepare_aave_repay` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-aave-repay.md - `prepare_btc_multisig_send` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-btc-multisig-send.md - `prepare_compound_repay` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-compound-repay.md - `prepare_compound_supply` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-compound-supply.md - `prepare_curve_swap` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-curve-swap.md - `prepare_custom_call` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-custom-call.md - `prepare_kamino_init_user` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-kamino-init-user.md - `prepare_kamino_supply` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-kamino-supply.md - `prepare_lido_unstake` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-lido-unstake.md - `prepare_lido_unwrap` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-lido-unwrap.md - `prepare_lido_wrap` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-lido-wrap.md - `prepare_native_stake_deactivate` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-native-stake-deactivate.md - `prepare_native_stake_delegate` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-native-stake-delegate.md - `prepare_rocketpool_unstake` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-rocketpool-unstake.md - `prepare_safe_tx_execute` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-safe-tx-execute.md - `prepare_solana_lifi_swap` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-solana-lifi-swap.md - `prepare_solana_nonce_init` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-solana-nonce-init.md - `prepare_solana_swap` — Execute — https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-solana-swap.md - …and 158 more: https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp.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=io-github-szhygulin-vaultpilot-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-szhygulin-vaultpilot-mcp