# prepare_tron_trc20_approve Build an unsigned TRC-20 approve(spender, amount) tx — sets allowance so a third party can pull tokens via transferFrom. Primary use: authorize the LiFi Diamond on TRON (TU3ymitEKCWQFtASkEeHaPb8NfZcJtCHLt) before running prepare_tron_lifi_swap with a TRC-20 source token (LiFi's quote response assumes the approve already exists; insufficient allowance reverts the swap on-chain). Accepts ANY TRC-20 contract — not just the canonical set. Decimals are auto-resolved for canonical USDT/USDC/USDD/TUSD; for any other TRC-20 you MUST pass decimals explicitly. We REFUSE to default decimals on approve because an off-by-power-of-ten allowance silently authorizes a 10^12-fold larger spend than intended, with no UX recovery on a Ledger blind-sign flow. amount is a human decimal string ("100" = 100 tokens at the resolved decimals). "max" / unbounded approvals are NOT supported — pass exactly the amount you intend to swap. Returns a preview + opaque handle for send_transaction. Agent View of the PolicyLayer registry record for `prepare_tron_trc20_approve`. HTML page: https://policylayer.com/tools/io-github-szhygulin-vaultpilot-mcp/prepare-tron-trc20-approve ## Facts - Tool: `prepare_tron_trc20_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 | | --- | --- | --- | --- | | `from` | string | yes | Base58 TRON owner address — the wallet that holds the tokens. | | `token` | string | yes | Base58 TRC-20 contract address. Any TRC-20 is accepted; non-canonical tokens require `decimals`. | | `amount` | string | yes | Allowance amount as a human-readable decimal string. Pass exactly the amount you intend to swap, NOT "max" / unbounded — TRC-20 unbounded approvals are a known | | `spender` | string | yes | Base58 TRON address authorized to pull tokens via transferFrom. Typical use: the LiFi Diamond on TRON (TU3ymitEKCWQFtASkEeHaPb8NfZcJtCHLt) for `prepare_tron_lif | | `decimals` | integer | no | Token decimals. OPTIONAL when `token` is in the canonical TRC-20 set (USDT/USDC=6, USDD/TUSD=18 — auto-resolved). REQUIRED for any other TRC-20 contract; we ref | | `feeLimitTrx` | string | no | Optional fee-limit override in TRX. Defaults to 100 TRX (TronLink/Ledger Live standard). | 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_tron_trc20_approve", "arguments": { "from": "", "token": "", "amount": "", "spender": "" } } } ``` ## Why prepare_tron_trc20_approve is rated Medium This tool creates a transaction that modifies token allowance state on-chain, enabling a third party (spender) to transfer tokens on behalf of the user. While the transaction is unsigned (requiring additional authorization), it constructs an irreversible financial commitment once signed and broadcast. From the tool's own definition: "Build an unsigned TRC-20 approve(spender, amount) tx — sets allowance so a third party can pull tokens via transferFrom. Authorize the LiFi Diamond on TRON to pull tokens." Risk signals: Handles credentials or secrets (token) ## Use case AI agents use prepare_tron_trc20_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_tron_trc20_approve": { "limits": [ { "counter": "prepare_tron_trc20_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