CornerStone MCP x402 Skill (for Agents)

This skill gives you (the agent) a set of tools to: create and manage Aptos and EVM wallets, check balances, and call x402-paid MCP tools (stock prediction, backtest, bank linking, agent/borrower scores). Payment is automatic — when a paid tool returns 402, the skill signs, verifies, settles, and retries transparently. You just call the tool; the result comes back.

Quick-start workflow

Follow this sequence on first use, then skip to the tool you need:

Check wallets → call
```
get_wallet_addresses
```
(no args).
If empty → call
```
create_aptos_wallet
```
then
```
create_evm_wallet
```
.
Fund → call
```
credit_aptos_wallet
```
(Aptos faucet) and
```
fund_evm_wallet
```
(EVM faucet instructions).
Tell the user to whitelist the returned addresses at
```
https://arnstein.ch/flow.html
```
.
Check balance → call
```
balance_aptos
```
(must have USDC for predictions/backtests) and/or
```
balance_evm
```
(must have ETH for bank linking).

Use paid tools →

run_prediction

run_backtest

link_bank_account

, or score tools.

Important: Paid tools will fail with a wallet/whitelist error if the address has not been funded and whitelisted. Always verify wallets and balances first.

Tool reference

Wallet management tools (local)

get_wallet_addresses

Args: none

Returns:

{ aptos: [{ address, network }], evm: [{ address, network }] }

— may be empty arrays.

When to use: Always call first before any wallet or paid tool action. Determines what exists.
Decision: If both arrays are empty → create wallets. If only one is empty → create the missing one. If both have entries → proceed to balance check or paid tools.

create_aptos_wallet

Args:

{ force?: boolean, network?: "testnet" | "mainnet" }

— defaults: force=false, network=testnet.

Returns:

{ success, address, network, message }

{ success: false, message, addresses }

if wallet exists and force=false.

When to use: When
```
get_wallet_addresses
```
returns empty
```
aptos
```
array, or user requests a new wallet.
Error handling: If
```
success: false
```
and wallet already exists, either use the existing wallet or retry with
```
force: true
```
to add another.

create_evm_wallet

Args:

{ force?: boolean, network?: "testnet" | "mainnet" }

— defaults: force=false, network=testnet.

Returns:

{ success, address, network, message }

{ success: false, message, addresses }

Same pattern as
```
create_aptos_wallet
```
.

credit_aptos_wallet

Args:
```
{ amount_octas?: number }
```
— default 100,000,000 (= 1 APT).
Returns on devnet:
```
{ success: true, address }
```
(programmatic faucet funded).
Returns on testnet:
```
{ success: true, address, faucet_url }
```
(instructions only; no programmatic faucet).
Prerequisite: Aptos wallet must exist (
```
create_aptos_wallet
```
first).
Note: Funded APT is for gas; tools pay in USDC (~6¢). The user may need to acquire testnet USDC separately.

fund_evm_wallet

Args: none

Returns:

{ success: true, address, faucet_url, message }

(manual funding instructions).

Prerequisite: EVM wallet must exist (
```
create_evm_wallet
```
first).
Note: Returns a Base Sepolia faucet URL. The user must fund manually; there is no programmatic faucet.

Balance tools (local)

balance_aptos

Args: none

Returns:

{ address, balances: { usdc, apt } }

{ error }

When to use: Before calling
```
run_prediction
```
,
```
run_backtest
```
, or score tools to confirm sufficient USDC.

balance_evm

Args:

{ chain?: string }

— default "base". Supported:

base

baseSepolia

ethereum

polygon

arbitrum

optimism

Returns:

{ address, chain, balance, symbol }

{ error }

When to use: Before calling
```
link_bank_account
```
to confirm sufficient ETH on Base Sepolia.
Note: For testnet tools, use
```
chain: "baseSepolia"
```
.

Paid MCP tools (x402 — payment handled automatically)

All paid tools accept both Aptos and EVM payment. The skill picks the best option or follows
PREFERRED_PAYMENT_ORDER
. You never see 402 errors — just call the tool and get the result or an error message.

run_prediction

Args:
```
{ symbol: string, horizon?: number }
```
— symbol is a stock ticker (e.g. "AAPL"), horizon is days (default 30).
Returns: Prediction result object (forecast data, confidence intervals, etc.) or
```
{ error }
```
.
Cost: ~6¢ USDC (Aptos or EVM).
Prerequisite: Funded + whitelisted Aptos or EVM wallet.

Example call:

run_prediction({ symbol: "AAPL", horizon: 30 })

run_backtest

Args:

{ symbol: string, startDate?: string, endDate?: string, strategy?: string }

— dates in "YYYY-MM-DD", strategy defaults to "chronos".

Returns: Backtest result (returns, drawdown, sharpe, etc.) or
```
{ error }
```
.
Cost: ~6¢ USDC.

Example call:

run_backtest({ symbol: "TSLA", startDate: "2024-01-01", endDate: "2024-12-31", strategy: "chronos" })

link_bank_account

Args: none
Returns:
```
{ link_token }
```
or account ID for Plaid bank linking, or
```
{ error }
```
.
Cost: ~5¢ (EVM/Base).
Prerequisite: Funded + whitelisted EVM wallet (Base Sepolia for testnet).

get_agent_reputation_score

Args:
```
{ agent_address?: string, payer_wallet?: string }
```
— both optional; uses the configured wallet if omitted.
Returns:
```
{ reputation_score: number }
```
(e.g. 100) or 403 if not allowlisted, or
```
{ error }
```
.
Cost: ~6¢ via x402, or free with lender credits (pass
```
payer_wallet
```
).

get_borrower_score

Args:

{ agent_address?: string, payer_wallet?: string }

— same pattern.

Returns:
```
{ score: number }
```
(100 base; higher with bank linked) or
```
{ error }
```
.
Cost: ~6¢ via x402, or free with lender credits.

get_agent_reputation_score_by_email

Args:
```
{ email: string, payer_wallet?: string }
```
— resolves email to allowlisted agent.
Returns:
```
{ reputation_score: number }
```
or
```
{ error }
```
.
Prerequisite:
```
SCORE_BY_EMAIL_ENABLED
```
must be set on the server. Higher fee.

get_borrower_score_by_email

Args:

{ email: string, payer_wallet?: string }

— same pattern.

Returns:
```
{ score: number }
```
or
```
{ error }
```
.
Prerequisite:
```
SCORE_BY_EMAIL_ENABLED
```
must be set on the server. Higher fee.

Decision tree for common tasks

"Run a prediction for X"

get_wallet_addresses
  → aptos empty? → create_aptos_wallet → credit_aptos_wallet → tell user to whitelist
  → aptos exists? → balance_aptos
    → has USDC? → run_prediction({ symbol: "X", horizon: 30 })
    → no USDC? → tell user to fund USDC, provide address

"Link a bank account"

get_wallet_addresses
  → evm empty? → create_evm_wallet → fund_evm_wallet → tell user to whitelist
  → evm exists? → balance_evm({ chain: "baseSepolia" })
    → has ETH? → link_bank_account
    → no ETH? → fund_evm_wallet (returns faucet URL)

"Get my scores"

get_wallet_addresses
  → has aptos or evm? → get_agent_reputation_score + get_borrower_score
  → neither? → create wallets first, whitelist, then query

Error handling

Error pattern	Meaning	What to do
`"No Aptos wallet"`	Wallet file missing	Call `create_aptos_wallet`
`"No EVM wallet"`	Wallet file missing	Call `create_evm_wallet`
`"already exist. Use force: true"`	Wallet exists, not overwriting	Use existing wallet, or pass `force: true` to add another
`"Payment verification failed"`	Insufficient funds or wrong asset	Check balance; tell user to fund the wallet
`"No Aptos wallet configured"` / `"No EVM wallet configured"`	Paid tool needs wallet that doesn't exist	Create the missing wallet type
`"Unsupported chain"`	Invalid chain name for `balance_evm`	Use one of: base, baseSepolia, ethereum, polygon, arbitrum, optimism
`"timed out after 300s"`	MCP call took too long	Retry once; the server may be under load
`"403"` or `"not allowlisted"`	Wallet not whitelisted	Tell user to whitelist address at https://arnstein.ch/flow.html

Setup (for the human installing this skill)

Install:
```
npm install
```
from repo root. Copy
```
.env.example
```
to
```
.env
```
.

Configure: Set wallet paths (

APTOS_WALLET_PATH

EVM_WALLET_PATH

EVM_PRIVATE_KEY

Wallets: Create via tools (
```
create_aptos_wallet
```
,
```
create_evm_wallet
```
) or CLI (
```
node src/setup-aptos.js
```
,
```
node src/setup.js
```
). Fund and whitelist all addresses at https://arnstein.ch/flow.html.

CLI commands (from repo root)

Task	Command
Generate Aptos wallet	`npm run setup:aptos`
Generate EVM wallet	`npm run setup`
Show addresses for whitelist	`npm run addresses`
Credit Aptos (devnet)	`npm run credit:aptos` (set `APTOS_FAUCET_NETWORK=devnet` )
EVM balance	`npm run balance -- <chain>`
Transfer ETH/tokens	`npm run transfer -- <chain> <to> <amount> [tokenAddress]`
Swap tokens (Odos)	`npm run swap -- <chain> <fromToken> <toToken> <amount>`
Run skill demo	`npx cornerstone-agent "Run a 30-day prediction for AAPL"`
Attest Aptos wallet	`npm run attest:aptos`
Attest EVM wallet	`npm run attest:evm`

Source: FinTechTonic/autonomous-agent

Autonomous Agent Skills

AI Skill Market Insights

Be Part of the 0+ Developer Community

CornerStone MCP x402 Skill (for Agents)

Quick-start workflow

Tool reference

Wallet management tools (local)

get_wallet_addresses

create_aptos_wallet

create_evm_wallet

credit_aptos_wallet

fund_evm_wallet

Balance tools (local)

balance_aptos

balance_evm

Paid MCP tools (x402 — payment handled automatically)

run_prediction

run_backtest

link_bank_account

get_agent_reputation_score

get_borrower_score

get_agent_reputation_score_by_email

get_borrower_score_by_email

Decision tree for common tasks

"Run a prediction for X"

"Link a bank account"

"Get my scores"

Error handling

Setup (for the human installing this skill)

CLI commands (from repo root)

Quick Start

Manual Installation

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`get_wallet_addresses`

`create_aptos_wallet`

`create_evm_wallet`

`credit_aptos_wallet`

`fund_evm_wallet`

`balance_aptos`

`balance_evm`

`run_prediction`

`run_backtest`

`link_bank_account`

`get_agent_reputation_score`

`get_borrower_score`

`get_agent_reputation_score_by_email`

`get_borrower_score_by_email`