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

Annotations already declare readOnly/destructive/openWorld, but the description adds real behavioral context: live on-chain read, a 422 for non-ERC-20 addresses with no charge, and per-call pricing with the first 25 free and failed calls free. That also explains why idempotentHint is false (repeats are billed). It does not describe output shape, though the field list largely covers 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?

Front-loaded with what it does, then the alternative route, then input format and cost. Mostly dense and purposeful, with minor duplication of the readOnly annotation in 'Reads or computes only and changes nothing' and a slightly long billing tail.

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, and the description compensates by listing the returned fields. For a one-parameter read tool, an agent has everything needed: input forms, error case, cost model, and a redirect for the adjacent balance query.

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 already documents that the argument accepts a ticker or 0x address, so the description mainly restates it. It still adds value with a concrete address example and the failure semantics (non-ERC-20 address returns 422 uncharged), which the schema does not convey.

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 HyperEVM, live from the contract. It explicitly names the sibling it is not (hyperevm_token_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?

Gives two concrete use cases (identify an unknown token address, format raw amounts) and an explicit exclusion pointing to hyperevm_token_balance for holder balances. Nothing about when to choose this vs. alternatives is left to inference.

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