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

Annotations already establish readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral context beyond the annotations: the pricing source (live DEX prices) and, critically, that the call costs $0.004 USDC on Base via x402 — a payment requirement an agent must know before invoking.

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 compact sentences, front-loaded with the value proposition, then input, then cost. Every clause carries information (token default, price source, payment) with no filler.

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 no output schema, the description does explain the return shape (each holding priced in USD, plus total) and covers input and payment cost. It is essentially complete for an agent to call it; only edge behavior (e.g., invalid address or unpriced tokens) is unspecified.

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 description must carry the load, and it largely does: 'address' is identified as the wallet address input and 'tokens' is explained as an optional set of up to 20 tokens you choose, with ETH plus major tokens as the default when omitted. Only the address format is left to the schema's pattern.

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 ('Wallet portfolio value on Base') and enumerates exactly what comes back: per-holding USD prices from live DEX prices plus the total. This clearly separates it from single-value siblings like base_balance, base_erc20_balance, and base_price.

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?

Usage is implied by the purpose — you call it when you want a full wallet valuation — and it names the required input ('Input: wallet address'). However, it never explicitly says when to prefer this over base_balance or base_erc20_balance for a single token, and gives no prerequisites or exclusions.

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