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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial context on top: data provenance (CDP Data API with Alchemy fallback, DexScreener for USD), the pricing model ($0.02/call via x402 on Base), the prepaid x-credit-token header for unlimited calls, no free tier, and no API key needed. That is exactly the behavioral detail annotations cannot express.

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?

Purpose is front-loaded and the payment/auth details follow in a compact block, but the opening repeats itself ('All ERC-20 holdings of a wallet with USD value' / 'Complete ERC-20 portfolio ... with ... live USD value'). One clause could be trimmed without loss.

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, return values need not be described, and the description still covers chain scope (Base), token coverage (every non-zero token), pricing, payment header, and data-source fallback. An agent has everything needed to decide and invoke 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?

There is a single parameter with 100% schema description coverage, so the schema already carries the semantics; 'Required input: address' restates it and adds nothing about format (checksummed vs lowercase, EOA vs contract). Baseline 3 for a fully documented 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?

The description states a specific verb+resource ('All ERC-20 holdings of a wallet') and pins the scope precisely: Base address, every non-zero token, balance + metadata + live USD value, plus a total. That 'complete portfolio with total' framing is enough to separate it from single-token siblings like token_balance or wallet_tokens without opening either schema.

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 says what input is required ('Required input: address') and how to pay, but never says when to pick this over alternatives such as wallet_networth (multi-chain net worth), wallet_tokens (raw balances) or portfolio_scan. Usage is implied by the scope statement rather than guided.

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