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

Beyond the read-only and idempotent annotations, the description discloses the x402 payment model, price per call, invalid-input refusal before payment, no charge for failed runs, and the PaymentRequired response when unpaid. These are important behavioral details an agent needs before invoking a paid tool.

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

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

The core purpose and return values are front-loaded, and the description is generally efficient. It includes some extra operational details such as the free sample call and HTTP URL, which are useful but not strictly necessary for MCP tool selection.

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

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

There is no output schema, but the description explains the return contents well: USDC amount, SOL/ETH fee balance, account existence, and x402 affordability. It also covers payment failure and invalid-input behavior, making it complete enough for an agent to call it correctly.

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

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

Schema coverage is 100% and both parameters are documented in the input schema, so the schema already carries most parameter semantics. The description adds workflow context for the optional amount parameter by explaining that it tests whether the wallet can pay a given x402 price, but does not add format or edge-case detail beyond that.

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

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

The description states a specific verb and resource: reading USDC and gas balances for any Solana or Base address. It also names exactly what is returned, including USDC amount, SOL/ETH fee balance, account existence, and x402 affordability. This clearly distinguishes it from sibling tools like network_fees or solana_portfolio.

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

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

It gives clear usage context: an agent can check its own funds or a counterparty before paying. It does not explicitly name when not to use it or compare directly against alternatives, but the use case is unambiguous.

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