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

Annotations already declare readOnlyHint and openWorldHint, but the description adds genuine operational context the annotations don't carry: x402 pricing ($0.005 USDC per call), that failed calls are free, and the quote-then-sign flow. It also discloses the thin-pool and oversized-position warning behavior. It stops short of describing latency, caching, or pool-source reliability.

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 with purpose, then pricing, then usage, then parameters and returns in clearly labeled blocks. Slight redundancy: the holdings/total/warnings output is stated both in the opening sentence and again in the Returns line, which costs a bit of space.

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?

There is no output schema, so the description carries the return contract and does so: holdings[] shape, the USD total, and the warning conditions. Combined with the pricing and payment workflow, an agent has everything needed to invoke it 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?

Schema coverage is 100%, so every parameter is already documented in the schema, including the base default, the 20-item token cap, and the address formats. The description restates these (address required, chain default, tokens up to 20) without adding format or syntax meaning beyond what the schema provides, so the baseline 3 applies.

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 ('Value a wallet in USD'), names the supported chains, and enumerates what is produced (per-holding prices, total, warnings). It explicitly differentiates itself from the sibling wallet_balance, so an agent can route 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?

Contains an explicit 'When to use' line and a 'Use instead' line naming wallet_balance with the selecting condition ('when amounts are enough (cheaper)'). No inference is required to choose between the two.

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