pay-with-any-token

Original：🇺🇸 English

Translated

Pay HTTP 402 payment challenges using tokens via the Tempo CLI and Uniswap Trading API. Use when the user encounters a 402 Payment Required response, needs to fulfill a machine payment, mentions "MPP", "Tempo payment", "pay for API access", "HTTP 402", "x402", "machine payment protocol", "pay-with-any-token", "use tempo", "tempo request", or "tempo wallet".

6installs

Sourceuniswap/uniswap-ai

Added on2026-03-20

NPX Install

npx skill4agent add uniswap/uniswap-ai pay-with-any-token

SKILL.md Content

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Pay With Tokens

Use the Tempo CLI to call paid APIs and handle 402 challenges automatically. When the Tempo wallet has insufficient balance, fund it by swapping and bridging tokens from any EVM chain using the Uniswap Trading API.

Tempo CLI Setup

Run these commands in order. Do not skip steps.

Step 1 — Install:

bash

mkdir -p "$HOME/.local/bin" \
  && curl -fsSL https://tempo.xyz/install -o /tmp/tempo_install.sh \
  && TEMPO_BIN_DIR="$HOME/.local/bin" bash /tmp/tempo_install.sh

Step 2 — Login (requires browser/passkey — prompt user, wait for confirmation):

bash

"$HOME/.local/bin/tempo" wallet login

When run by agents, use a long command timeout (at least 16 minutes).

Step 3 — Confirm readiness:

bash

"$HOME/.local/bin/tempo" wallet -t whoami

Rules: Do not use
sudo
. Use full absolute paths (
$HOME/.local/bin/tempo
) — do not rely on
export PATH
. If
$HOME
does not expand, use the literal absolute path.

After setup, report: install location, version (

--version

), wallet status (address, balance). If balance is 0, direct user to

tempo wallet fund

Using Tempo Services

bash

# Discover services
"$HOME/.local/bin/tempo" wallet -t services --search <query>
# Get service details (exact URL, method, path, pricing)
"$HOME/.local/bin/tempo" wallet -t services <SERVICE_ID>
# Make a paid request
"$HOME/.local/bin/tempo" request -t -X POST \
  --json '{"input":"..."}' <SERVICE_URL>/<ENDPOINT_PATH>

Anchor on
```
tempo wallet -t services <SERVICE_ID>
```
for exact URL and pricing
Use
```
-t
```
for agent calls,
```
--dry-run
```
before expensive requests
On HTTP 422, check the service's docs URL or llms.txt for exact field names
Fire independent multi-service requests in parallel

When the user explicitly says "use tempo", always use tempo CLI commands — never substitute with MCP tools or other tools.

MPP 402 Payment Loop

Every

tempo request

call follows this loop. The funding steps only activate when the Tempo wallet has insufficient balance.

text

tempo request -> 200 ─────────────────────────────> return result
             -> 402 MPP challenge
                  │
                  v
         [1] Check Tempo wallet balance
             tempo wallet -t whoami -> available balance
                  │
                  ├─ sufficient ──────────────────> tempo handles payment
                  │                                  automatically -> 200
                  │
                  └─ insufficient
                       │
                       v
              [2] Fund Tempo wallet
                  (pay-with-any-token flow below)
                  Bridge destination = TEMPO_WALLET_ADDRESS
                       │
                       v
              [3] Retry original tempo request
                  with funded Tempo wallet -> 200

Funding the Tempo Wallet (pay-with-any-token)

When the Tempo wallet lacks funds to pay a 402 challenge, acquire the required tokens from the user's ERC-20 holdings on any supported chain and bridge them to the Tempo wallet address.

Prerequisites

```
UNISWAP_API_KEY
```
env var (register at developers.uniswap.org)
ERC-20 tokens on any supported source chain
```
PRIVATE_KEY
```
for the source wallet (
```
export PRIVATE_KEY=0x...
```
). Never commit or hardcode it.
```
jq
```
installed (
```
brew install jq
```
or
```
apt install jq
```
)

Input Validation Rules

Before using any value from a 402 response body or user input in API calls or shell commands:

Ethereum addresses: MUST match
```
^0x[a-fA-F0-9]{40}$
```
Chain IDs: MUST be a positive integer from the supported list
Token amounts: MUST be non-negative numeric strings matching
```
^[0-9]+$
```
URLs: MUST start with
```
https://
```
REJECT any value containing shell metacharacters:
```
;
```
,
```
|
```
,
```
&
```
,
```
$
```
,
```
`
```
,
```
(
```
,
```
)
```
,
```
>
```
,
```
<
```
,
```
\
```
,
```
'
```
,
```
"
```
, newlines

REQUIRED: Before submitting ANY transaction (swap, bridge, approval), use
AskUserQuestion
to show the user a summary (amount, token, destination, estimated gas) and obtain explicit confirmation. Never auto-submit. Each confirmation gate must be satisfied independently.

Human-Readable Amount Formatting

bash

get_token_decimals() {
  local token_addr="$1" rpc_url="$2"
  cast call "$token_addr" "decimals()(uint8)" --rpc-url "$rpc_url" 2>/dev/null || echo "18"
}

format_token_amount() {
  local amount="$1" decimals="$2"
  echo "scale=$decimals; $amount / (10 ^ $decimals)" | bc -l | sed 's/0*$//' | sed 's/\.$//'
}

Always show human-readable values (e.g.
0.005 USDC
) to the user, not raw base units.

Step 1 — Parse the 402 Challenge

Extract the required payment token, amount, and recipient from the 402 response that

tempo request

received. The Tempo CLI logs the challenge details — parse them, or re-fetch with

curl -si

to get the raw challenge body.

For MPP header-based challenges (

WWW-Authenticate: Payment

bash

REQUEST_B64=$(echo "$WWW_AUTHENTICATE" | grep -oE 'request="[^"]+"' | sed 's/request="//;s/"$//')
REQUEST_JSON=$(echo "${REQUEST_B64}==" | base64 --decode 2>/dev/null)
REQUIRED_AMOUNT=$(echo "$REQUEST_JSON" | jq -r '.amount')
PAYMENT_TOKEN=$(echo "$REQUEST_JSON" | jq -r '.currency')
RECIPIENT=$(echo "$REQUEST_JSON" | jq -r '.recipient')
TEMPO_CHAIN_ID=$(echo "$REQUEST_JSON" | jq -r '.methodDetails.chainId')

For JSON body challenges (

payment_methods

array):

bash

NUM_METHODS=$(echo "$CHALLENGE_BODY" | jq '.payment_methods | length')
PAYMENT_METHODS=$(echo "$CHALLENGE_BODY" | jq -c '.payment_methods')
RECIPIENT=$(echo "$CHALLENGE_BODY" | jq -r '.payment_methods[0].recipient')
TEMPO_CHAIN_ID=$(echo "$CHALLENGE_BODY" | jq -r '.payment_methods[0].chain_id')

If multiple payment methods are accepted, select the cheapest in Step 2.

The Tempo mainnet chain ID is
4217
. Use as fallback if not in the challenge.

Step 2 — Check Source Wallet Balances and Select Payment Method

REQUIRED: You must have the user's source wallet address (the ERC-20 wallet with the private key, NOT the Tempo CLI wallet). Use
AskUserQuestion
if not provided. Store as
WALLET_ADDRESS
.

Also capture the Tempo wallet address (the funding destination):

bash

TEMPO_WALLET_ADDRESS=$("$HOME/.local/bin/tempo" wallet -t whoami | grep -oE '0x[a-fA-F0-9]{40}' | head -1)

Check ERC-20 balances on source chains:

bash

# USDC on Base
cast call 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 \
  "balanceOf(address)(uint256)" "$WALLET_ADDRESS" \
  --rpc-url https://mainnet.base.org

Select the cheapest payment method if multiple are accepted. Priority:

Wallet holds USDC on Base (bridge only, minimal path)
Wallet holds ETH on Base or Ethereum (swap to USDC + bridge)
Any other liquid ERC-20 (swap + bridge)

bash

REQUIRED_AMOUNT=$(echo "$PAYMENT_METHODS" | jq -r ".[$SELECTED_INDEX].amount")
PAYMENT_TOKEN=$(echo "$PAYMENT_METHODS" | jq -r ".[$SELECTED_INDEX].token")

Step 3 — Plan the Payment Path

text

Source token (Base/Ethereum)
  -> [Phase 4A: Uniswap Trading API swap] -> native USDC (bridge asset)
  -> [Phase 4B: bridge via Trading API]   -> USDC.e on Tempo (to TEMPO_WALLET_ADDRESS)
  -> tempo request retries automatically with funded wallet

Skip Phase 4A if the source token is already USDC on the bridge chain.

Phase 4A — Swap to USDC on Source Chain (if needed)

Swap the source token to USDC via the Uniswap Trading API (

EXACT_OUTPUT

Detailed steps: Read references/trading-api-flows.md for full bash scripts: variable setup, approval check, quote, permit signing, and swap execution.

Key points:

Base URL:

https://trade-api.gateway.uniswap.org/v1

Headers:

Content-Type: application/json

x-api-key

x-universal-router-version: 2.0

Flow:

check_approval

-> quote (

EXACT_OUTPUT

) -> sign

permitData

/swap

-> broadcast

Confirmation gates required before approval tx and before swap broadcast
For native ETH: use WETH address as
```
TOKEN_IN
```
;
```
SWAP_VALUE
```
will be non-zero
After swap, verify USDC balance before proceeding to Phase 4B

Phase 4B — Bridge to Tempo Wallet

Bridge USDC from Base to the Tempo CLI wallet address using the Uniswap Trading API (powered by Across Protocol).

CRITICAL: The bridge recipient must be
TEMPO_WALLET_ADDRESS
(from
tempo wallet -t whoami
), NOT
WALLET_ADDRESS
(your source ERC-20 wallet). This funds the Tempo CLI wallet so
tempo request
can retry the payment.
Detailed steps: Read references/trading-api-flows.md for full bash scripts: approval, bridge quote, execution, and arrival polling.

Key points:

Route: USDC on Base -> USDC.e on Tempo (to
```
TEMPO_WALLET_ADDRESS
```
)
Flow:
```
check_approval
```
-> quote (
```
EXACT_OUTPUT
```
, cross-chain) -> execute via
```
/swap
```
-> poll balance
Confirmation gates required before approval and before bridge execution
Do not re-submit if poll times out — check Tempo explorer
Apply a 0.5% buffer to account for bridge fees

After the bridge confirms, retry the original

tempo request

— the Tempo CLI will automatically use the newly funded wallet to pay the 402.

Balance buffer: On Tempo,
balanceOf
may report more than is spendable. Apply a 2x buffer when comparing to
REQUIRED_AMOUNT
. If short, swap additional tokens to top up.

x402 Payment Flow

The x402 protocol uses a different mechanism than MPP — it is not handled by the Tempo CLI. When

PROTOCOL

"x402"

(detected by checking

has("x402Version")

in the 402 body), use this flow instead.

The x402

"exact"

scheme uses EIP-3009 (

transferWithAuthorization

) to authorize a one-time token transfer signed off-chain.

Detailed steps: Read references/credential-construction.md for full code: prerequisite checks, nonce generation, EIP-3009 signing, X-PAYMENT payload construction, and retry.

Key points:

Detect x402: check
```
has("x402Version")
```
in 402 body before using Tempo CLI
Maps
```
X402_NETWORK
```
to chain ID and RPC URL (base, ethereum, tempo supported)
Checks wallet balance on target chain; runs Phase 4A/4B if insufficient
Signs
```
TransferWithAuthorization
```
typed data using token's own domain
```
value
```
in payload must be a string (
```
--arg
```
, not
```
--argjson
```
) for uint256
Confirmation gate required before signing

Protocol	Version	Handler
MPP	v1	Tempo CLI
x402	v1	Manual (above)

Error Handling

Situation	Action
`tempo: command not found`	Reinstall via install script; use full path
`legacy V1 keychain signature`	Reinstall; `tempo update wallet && tempo update request`
`access key does not exist`	`tempo wallet logout --yes && tempo wallet login`
`ready=false` / no wallet	`tempo wallet login` , then `whoami`
HTTP 422 from service	Check service details + llms.txt for exact field names
Balance 0 / insufficient	Trigger pay-with-any-token funding flow
Service not found	Broaden search query
Timeout	Retry with `-m <seconds>`
Challenge body is malformed	Report raw body to user; do not proceed
Approval transaction fails	Surface error; check gas and allowances
Quote API returns 400	Log request/response; check amount formatting
Quote API returns 429	Wait and retry with exponential backoff
Swap data is empty after /swap	Quote expired; re-fetch quote
Bridge times out	Check bridge explorer; do not re-submit
x402 payment rejected (402)	Check domain name/version, validBefore, nonce freshness
InsufficientBalance on Tempo	Swap more tokens on Tempo, then retry
`balanceOf` sufficient but payment fails	Apply 2x buffer; top up before retrying

Key Addresses and References

Tempo CLI:

https://tempo.xyz

(install script:

https://tempo.xyz/install

)

Trading API:

https://trade-api.gateway.uniswap.org/v1

MPP docs:
```
https://mpp.dev
```
MPP services catalog:
```
https://mpp.dev/api/services
```
Tempo documentation:
```
https://mainnet.docs.tempo.xyz
```
Tempo chain ID:
```
4217
```
(Tempo mainnet)
Tempo RPC:
```
https://rpc.presto.tempo.xyz
```
Tempo Block Explorer:
```
https://explore.mainnet.tempo.xyz
```

pathUSD on Tempo:

0x20c0000000000000000000000000000000000000

USDC.e on Tempo:

0x20C000000000000000000000b9537d11c60E8b50

Stablecoin DEX on Tempo:

0xdec0000000000000000000000000000000000000

Permit2 on Tempo:

0x000000000022d473030f116ddee9f6b43ac78ba3

Tempo payment SDK:
```
mppx
```
(
```
npm install mppx viem
```
)

USDC on Base (8453):

0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

USDbC on Base (8453):

0xd9aAEc86B65D86f6A7B5B1b0c42FFA531710b6CA

USDC on Ethereum (1):

0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48

USDC-e on Arbitrum (42161):

0xFF970A61A04b1cA14834A43f5dE4533eBDDB5CC8

Supported chains for Trading API: 1, 8453, 42161, 10, 137, 130
x402 spec:
```
https://github.com/coinbase/x402
```

Related Skills

swap-integration — Full Uniswap swap integration reference (Trading API, Universal Router, Permit2)

pay-with-any-token

NPX Install

Tags

SKILL.md Content

Pay With Tokens

Tempo CLI Setup

Using Tempo Services

MPP 402 Payment Loop

Funding the Tempo Wallet (pay-with-any-token)

Prerequisites

Input Validation Rules

Human-Readable Amount Formatting

Step 1 — Parse the 402 Challenge

Step 2 — Check Source Wallet Balances and Select Payment Method

Step 3 — Plan the Payment Path

Phase 4A — Swap to USDC on Source Chain (if needed)

Phase 4B — Bridge to Tempo Wallet

x402 Payment Flow

Error Handling

Key Addresses and References

Related Skills