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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), yet the description adds real value beyond them: per-call price and free tier, the x402 payment-required path, and the error contract (isError on invalid input or upstream failure, and that failures are not charged).

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 what is returned, then labeled 'When to use', 'Price', and 'Errors' sections that make skimming easy. Slightly dense and dash-heavy in the opening sentence, but 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?

An output schema exists, so return-value explanation is unnecessary. Combined with full parameter coverage, annotations, and the cost/error disclosure, 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 description coverage is 100%, so chain/token/wallet are fully documented in the schema and the enum is self-evident. The description only restates that a wallet balance is retrievable, adding no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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 exactly what is returned (name, symbol, decimals, total supply, USD price, wallet balance) and the mechanism (direct contract calls priced via DefiLlama). It distinguishes itself from the nearest sibling, evm_token_security, by name.

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?

Explicit 'When to use: For token facts; for scam/honeypot checks use evm_token_security' gives both the condition and the alternative. The 'works for any token, listed or not' clause further clarifies eligibility.

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