Pay-per-call tools for AI agents via x402 (USDC on Base): current gas and fee tiers plus USD transaction costs on Base, Ethereum, Arbitrum, Optimism, Polygon and Solana; cheapest-chain ranking for a transfer, USDC transfer or swap; and web page to clean Markdown. Free list_chains tool. Failed calls are not charged.
Scored across 7 tools
The tools split into two clear clusters: URL preflight/extraction and gas/chain pricing. Within each cluster, the descriptions sharply distinguish use cases, such as get_gas_price vs compare_gas_costs vs estimate_custom_tx_cost, and check_url_status vs read_url_as_markdown. The only mild overlap is get_native_token_price with the nativeUsd field returned by gas tools, but the description explicitly frames it as a cheaper alternative when gas data is not needed.
All seven tools use snake_case and begin with a clear verb: check, compare, estimate, get, list, read. The pattern is predictable across both domains, with no camelCase or mixed verb-style inconsistencies. Longer names like read_url_as_markdown remain readable and follow the same convention.
Seven tools is well-scoped for a utility server covering URL reading and multi-chain gas estimation. Each tool has a distinct role, and there is no obvious redundant or trivial tool. The count supports both domains without feeling bloated.
The set covers the apparent core lifecycle: list chains, get one chain's gas prices, compare all chains, estimate custom transaction costs, get native token price, preflight a URL, and extract page Markdown. Minor gaps remain, such as no non-native token price lookup and no explicit OP-stack L1 data fee handling, but the latter is called out with a workaround. These are small enough that agents can generally proceed without dead ends.
Check if a URL is reachable before paying to read it. HEAD request following up to five redirects: status code, final URL, content-type, content-length and last-modified — no page body fetched or charged for content. Use before read_url_as_markdown ($0.003) to confirm a URL resolves and is HTML before paying the bigger fee for extraction. Doesn't check robots.txt (that's enforced on the actual read). Some servers reject HEAD (405/403) even though GET works, so a non-2xx here doesn't guarantee read_url_as_markdown will also fail. Costs $0.001 USDC per call (x402).
Inputs: url (required).
Where is it cheapest to send this transaction right now?. Ranks all 6 supported chains (Base, Ethereum, Arbitrum, Optimism, Polygon, Solana) by USD cost for a transaction type (transfer, USDC transfer or swap) at a speed tier (slow/standard/fast). Returns the ranking, the cheapest chain, and any chains queried in parallel that didn't respond (in failed[]). Costs $0.005 USDC per call (x402).
Inputs: tx, tier.
USD cost of a custom gas limit or compute-unit budget. Prices an arbitrary transaction, not just the 3 canned types get_gas_price/compare_gas_costs cover: pass your own gas limit (EVM chains) or compute-unit budget (Solana) and get its USD cost at a speed tier. Use this for a contract call, NFT mint or any tx whose gas usage you already know or estimated via eth_estimateGas/simulation — get_gas_price's 3 canned tx types won't fit it. Typical EVM units: 21,000 plain transfer, 50,000-65,000 ERC20 transfer, 100,000-250,000 typical contract call/NFT mint, 150,000-400,000 DEX swap; typical Solana compute units: 200,000 simple transfer, up to 1,400,000 (the per-tx cap) for a complex instruction. Excludes OP-stack L1 data fee (depends on calldata size, not gas limit) — add a few % for Base/Optimism to be safe. Costs $0.002 USDC per call (x402).
Inputs: chain (required), units (required), tier.
Current gas/fee tiers and USD costs for one chain. Slow/standard/fast gas tiers and USD cost of a transfer, USDC transfer and swap, for Base, Ethereum, Arbitrum, Optimism, Polygon or Solana. Updated every 15s. Solana is compute-unit pricing, not gwei-style gas; the other 5 are EVM. Use for one chain's prices; use compare_gas_costs to rank all 6, or estimate_custom_tx_cost for a gas limit/compute budget outside the 3 canned tx types here. x402: 402 first, retry with PAYMENT-SIGNATURE (MCP: _meta["x402/payment"]) — unpaid/failed calls are never charged. Costs $0.002 USDC per call (x402).
Inputs: chain (required).
USD price of a chain's native token, no gas data. Just the native-token USD price (ETH, POL or SOL), sourced from MEXC/Gate.io/Coinbase with the same price feed get_gas_price uses. Use this when you only need the asset price, not fees — get_gas_price and compare_gas_costs already return nativeUsd alongside gas data, so call this instead only to skip the gas lookup (e.g. valuing a wallet balance, not estimating a transaction). Costs $0.001 USDC per call (x402).
Inputs: chain (required).
List supported chains (Base, Ethereum, Arbitrum, Optimism, Polygon, Solana) and the gas-unit constants used by the paid tools (free). Always returns the full, unfiltered list of all 6 chains (no input/filter params). gasUnits.{transfer|usdc_transfer|swap} are plain integers: the gas units a typical transaction of that type costs on an EVM chain (evm) or in Solana compute units (svm) — multiply by the chain's current fee from get_gas_price to estimate USD cost yourself, or just call get_gas_price/compare_gas_costs which already does this.
Inputs: no named parameters.
Convert any web page into clean, readable Markdown. Fetches a public web page and returns clean Markdown: title, byline, site name, excerpt, word count and article body. Respects robots.txt, blocks private hosts, follows up to five redirects, caps the page at 3 MB. links=true adds outbound links. Not charged on failure: 403 if robots.txt disallows the path, 415 for non-HTML, 422 if no article text extracts, 502 on upstream error. Costs $0.003 USDC per call (x402).
Inputs: url (required), links.
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