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

Annotations cover read-only and open-world, but the description adds genuinely new facts: the result is formatted with token symbol and decimals (no output schema exists), and the call is a paid x402 endpoint costing $0.002 USDC on Base. That payment/auth context is not derivable from any structured field, though error and failure behavior go unmentioned.

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, front-loaded with what the tool returns before inputs and price. The middle 'Input:' sentence restates the schema's two property names and is the only mildly expendable line.

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?

For a simple two-parameter read with no output schema, the description supplies output formatting, the two inputs, and the payment model. Coverage is solid; only failure modes and any rate/latency expectations are missing.

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 0%, so the schema gives only names and a hex pattern. The description compensates partially by clarifying address = wallet address and token = token contract address, but adds no detail on the expected ERC-20 contract semantics or chain caveats.

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: the ERC-20 token balance of a wallet on Base, and clarifies it covers any token, not just USDC. This implicitly separates it from base_balance (native asset) and base_allowance, though it never names those siblings outright.

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 description only says which inputs to supply; it gives no conditions for choosing this tool over base_balance, base_portfolio, or base_allowance, and no exclusions. An agent must infer that ERC-20 vs native balance is the dividing line.

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