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

Annotations only cover read-only/safety; the description adds the failure mode (non-ERC-20 address returns 422, uncharged), the pricing model ($0.01/call, first 25 free, failed calls free) and the reason repeats are not free, which explains the idempotentHint=false annotation rather than contradicting it.

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 and the sibling hand-off are front-loaded in the first two sentences. The tail is a dense run-on packing error code, example, pricing and a read-only reassurance; every element is useful but could be split for readability.

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?

For a one-parameter, read-only lookup with no output schema, the description effectively enumerates the returned fields, covers the input format ambiguity, the error case, and cost. An agent has everything needed to call it correctly and interpret the result.

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% and the schema's own description already says the parameter accepts a ticker or a 0x ERC-20 address. The description's example address adds a small amount of concreteness but no new syntax or formatting rules, so the baseline of 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 a specific verb and resource: look up name, symbol, decimals and total supply of an ERC-20 contract on Unichain, read live from the contract. It explicitly separates itself from unichain_token_balance by naming that sibling and its different output.

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?

Gives two concrete use cases (identifying an unknown token address, formatting raw amounts) and an explicit alternative with the condition that selects it: 'for a holder's balance use unichain_token_balance'. Nothing is left to inference about when to pick this tool.

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