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

Annotations already declare readOnly/openWorld/non-destructive, but the description adds what the payload reports, error behavior (malformed address → 400, uncharged), and the billing model (price per call, first 25 free, failures free). It even reconciles the non-idempotent billing effect with 'reads or computes only and changes nothing'.

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 and usage, then behavior, then pricing. Every clause carries information, though the pricing/credit sentence is dense and slightly competes with the core purpose for attention.

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 tool with no output schema, the description fully covers return contents, failure mode, cost, and the alternative tool. Nothing needed to call it correctly is missing.

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 the baseline is 3; the description goes beyond it by giving a concrete example address and specifying how an invalid address is handled (rejected with 400, uncharged). It does not document expected address formats beyond '0x', which keeps it from a 5.

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 ('Check whether a 0x address on Ink is a smart contract or a plain wallet') and enumerates what the answer contains: bytecode size, EIP-1167 detection, and implementation address. This clearly separates it from sibling reads like ink_balance or ink_proxy.

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 explicit when-to-use ('before sending funds or approving a spender') and names the alternative for a different need ('for a fuller risk verdict use check_counterparty'). The agent knows both the trigger case and the escape hatch.

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