Laso Finance

pay_x402_endpoint

Destructive

Pay ANY external x402-paywalled endpoint from your managed agent wallet: the target's 402 challenge is settled in USDC and the response body is returned, with the settlement transaction as txHash. Endpoints settling in USDC on Solana or on Base mainnet (eip155:8453) are both paid from the same balance with nothing to set up: when a Base payment needs more than the Base side holds, the difference is moved over from Solana just before signing (usually under 10 seconds, 0.075% of the amount moved). No ETH is needed for gas; other EVM networks are refused. If the endpoint offers both, pin expected_network to choose. txHash is the Base transaction hash for a Base payment and the Solana signature for a Solana one. The wallet balance can take up to a minute to reflect a payment, so confirm with txHash rather than an immediate balance read. Use the guardrail arguments to pin what you agreed to pay. For Laso's own paid routes, prefer their dedicated tools instead.

Input Schema

Name	Required	Description
`url`	Yes	Full https URL of the x402 endpoint to call and pay.
`body`	No	JSON request body (for POST/PUT).
`method`	No	HTTP method (default GET).
`params`	No	Query parameters to append to the URL.
`expected_asset`	No	Refuse to settle in any other asset (e.g. a USDC mint/contract address; USDC on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913).
`expected_pay_to`	No	Refuse to settle to any other receiving address.
`max_amount_usdc`	No	Refuse to settle if the endpoint asks for more USDC than this.
`expected_network`	No	Refuse to settle on any other network (CAIP-2 id): eip155:8453 for Base, solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp for Solana. Pin it when an endpoint offers both, to choose which wallet pays.

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 13, 2026

changedInput schema / properties / expected_asset / description

Previous value: -"Refuse to settle in any other asset (e.g. a USDC mint/contract address)."New value: +"Refuse to settle in any other asset (e.g. a USDC mint/contract address; USDC on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913)."

changedInput schema / properties / expected_network / description

Previous value: -"Refuse to settle on any other network (CAIP-2 id)."New value: +"Refuse to settle on any other network (CAIP-2 id): eip155:8453 for Base, solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp for Solana. Pin it when an endpoint offers both, to choose which wallet pays."

Changed2 schema fields changedSep 26, 2026

removedInput schema / properties / auth_token

Removed value: -{
-  "description": "Laso credential. Only if the MCP connection has no Authorization header.",
-  "type": "string"
-}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "type": "object"
+}

Changed1 schema field changedSep 26, 2026
- changedOutput schema / (root)
```
Previous value: -{
-  "type": "object"
-}New value: +null
```
First observedSep 26, 2026

TDQS

A4.8/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare the destructive/non-idempotent/open-world profile, and the description layers on behavior annotations cannot express: USDC settlement, auto-bridging from Solana to Base with ~10s and 0.075% cost, no ETH gas needed, other EVM networks refused, and up-to-a-minute balance lag with a txHash-based verification recommendation. This is materially useful operational context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action, then settlement/fee/latency caveats, then guardrail guidance and the sibling redirect. Every sentence carries information, though the long run-on paragraph is denser than ideal for scanning; a small trim or list would sharpen it.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For an 8-parameter, open-world payment tool with an output schema already describing the return, the description covers the remaining agent questions: cost, latency, gas, network refusal, balance-lag caveat, and verification via txHash. Nothing needed to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning beyond the schema: guardrail arguments exist to 'pin what you agreed to pay,' expected_network controls which wallet funds the payment when both networks are offered, and txHash format varies by network (Base hash vs Solana signature).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource+scope: 'Pay ANY external x402-paywalled endpoint from your managed agent wallet.' It also distinguishes itself from siblings by telling the agent that Laso's own paid routes have dedicated tools. An agent can select this tool over 60+ siblings without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use ('Pay ANY external x402-paywalled endpoint'), when an alternative applies ('For Laso's own paid routes, prefer their dedicated tools instead'), and a decision rule for a real ambiguity ('If the endpoint offers both, pin expected_network to choose'). Nothing about routing is left to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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