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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), yet the description adds real operational context: cost model ($0.02/call over x402 on Base), the auth mechanism (prepaid x-credit-token header for unlimited calls), absence of a free tier, and no API key requirement. It also discloses an important data-handling edge case: unquoted holdings are listed and counted separately instead of being silently valued at zero.

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?

Front-loaded summary followed by scope, edge-case behavior, and payment terms; no filler or repetition. The billing/header sentence is slightly dense but it is genuinely load-bearing information an agent needs before calling a paid endpoint.

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 need not explain return values, and it correctly focuses on coverage, ordering, totals, unquoted-holding handling, and payment/auth requirements. Nothing an agent needs in order to call this correctly is 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 description coverage is 100% for the single 'address' parameter, so the schema does the documentation work and the 3 baseline applies. The description adds only marginal meaning — 'Required input: address' plus the implicit 'Base address' chain constraint — and gives no format or validation detail beyond the schema.

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-like outcome and resource: 'Complete token portfolio for a Base address with USD values', enumerating scope (every ERC-20 plus native ETH, sorted by value with a total). An agent can tell this is a priced valuation snapshot rather than a raw balance list. It never names the adjacent siblings (wallet_tokens, wallet_portfolio, token_balance) to disambiguate, so it stops short of a 5.

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 scope statement — use it when you need USD-valued holdings for a Base wallet — and the pricing sentences signal that cost matters. But there is no explicit when-to-use/when-not, no prerequisites, and no routing to alternatives among the many wallet_* siblings. Adequate but leaves selection to inference.

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