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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered structurally. The description adds the Base-mainnet scoping and the default $0.001 amount, but reveals nothing about rate limits, failure modes, or how shortfall is computed.

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?

Three short sentences with the core purpose front-loaded and no wasted clauses. The trailing sample-endpoint pointer is marginally useful but slightly off-topic for a parameter-level description.

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?

With an output schema present, the description needn't enumerate returns, and it still names the key fields (balance, can_pay, shortfall). Annotations cover the safety profile, so almost everything an agent needs is present, though it omits any note about chain scope limits or error responses.

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 description coverage is 100% for both parameters, including the 0.001 default, so the description's mention of the default simply repeats the schema. Baseline 3 is appropriate since the schema does the heavy lifting.

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?

States a specific verb+resource ('Check whether a Base wallet holds enough USDC to pay an x402 amount') and names the decision it feeds (can_pay/shortfall). It is clearly distinguishable from the sibling wallet_balance, which reports holdings rather than a spendability verdict.

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?

'The checklist agents run before spending' gives a clear usage context (pre-transaction preflight). It does not name an explicit alternative or a when-not-to-use condition, so it falls short of full routing guidance.

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