x402-wallet-mcp

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Get wallet balance

get_wallet_balance

Read-only

Retrieve a wallet's USDC balance across supported chains, or query a specific CAIP-2 chain, to verify funds before making x402 payments.

Instructions

Shows the wallet's USDC balance on every supported chain (plus other tokens the provider reports).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "get_wallet_balance"
  }
}

Input Schema

Name	Required	Description	Default
`chain`	No	CAIP-2 chain id, e.g. "eip155:84532" (Base Sepolia) or "eip155:8453" (Base). Omit for all chains.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 7, 2026

TDQS

B3.4/5.0

Behavior3/5

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

The readOnlyHint annotation already establishes this as a safe read. The description adds real value by disclosing that results span every supported chain and may include non-USDC tokens the provider reports, but it says nothing about failure modes (unsupported chain id, missing wallet) or result shape/pagination.

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?

One front-loaded sentence with no filler; the verb, resource, and scope come first. The trailing parenthetical about other tokens is slightly loose but carries genuine information about the payload.

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

Completeness3/5

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

A simple, single-optional-parameter read tool with no output schema needs little more, and the description covers scope and default behavior. It stops short of noting what an agent should expect if the chain id is invalid or if a chain is unsupported, which would round it out.

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

Parameters3/5

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

Schema coverage is 100%, so the single optional chain parameter is already fully documented with CAIP-2 examples and the omit-for-all behavior. The description's "on every supported chain" merely echoes that default, adding no new syntax or format detail. Baseline 3 is appropriate.

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

Purpose4/5

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

States a specific verb+resource ("Shows the wallet's ... balance") and the scope ("on every supported chain"), plus a qualifier that other tokens may appear. It is clearly distinct from siblings like get_wallet_address or check_payment_requirements, though it never names an alternative explicitly.

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

Usage Guidelines3/5

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

Usage is only implied: an agent can infer it should call this to check funds, and the schema note "Omit for all chains" covers the default. There is no explicit when-to-use/when-not-to-use guidance or pointer to a sibling for per-chain or per-token detail.

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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