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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open world), yet the description still adds substantial context: which chains are read, which assets are covered, error behavior (400 on invalid address, not charged), and paid-call mechanics ($0.04 via x402, USDC on Base only). This is well beyond what structured fields convey.

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 in the first two words, then usage, input contract, data scope, return shape, safety, and pricing follow in tight order. The dense return-field enumeration reflects the absence of an output schema, so no sentence is 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 carries the return-value burden and does: holdings fields, totals, concentration score and band, and rule findings. Payment model, error semantics, and chain coverage are all addressed, so an agent has everything needed to invoke and interpret it.

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 100% on the single `address` parameter, which sets the baseline at 3. The description adds meaning the schema lacks — the explicit 40-hex format requirement ('0x... (40 hex)') and that the address is snapshotted on both Base and Ethereum — earning a bump.

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 and resource ('Wallet balance checker') and narrows scope to 'token holdings and USD value of one EVM address'. It is clear what the tool does, but it never distinguishes itself from the sibling tool named `balance`, which an agent could easily confuse it with.

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 sentence 'Use when you need the token holdings and USD value of one EVM address' gives a concrete triggering condition. It stops short of the 5 bar because it names no alternative or exclusion, despite a near-identically named sibling (`balance`) that begs for disambiguation.

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