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

Annotations already declare readOnly/openWorld, but the description goes well beyond them: it discloses error semantics (404 for no contract, 422 for non-ERC-20, both uncharged), pricing ($0.01/call, first 25 free, failed calls free), and that repeats are billed — which usefully explains the non-obvious idempotentHint=false.

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 and the sibling routing, then pricing/error details last — correct ordering. It is dense and packs pricing, error codes, and validation into one paragraph, so a little tightening would help, but no sentence is pure 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?

No output schema exists, yet the description enumerates the return shape (raw amount, decimals, symbol, human-readable amount). Combined with auth/billing and error behavior, an agent has everything needed to call it 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%, so the baseline is 3. The description adds address validation ('40 hex characters') but then says 'Both inputs are 0x addresses', which conflicts with the schema's statement that token may be a ticker like USDC/USDT — that ambiguity slightly undercuts rather than sharpens parameter meaning.

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+resource (read ERC-20 balanceOf for a wallet on Ink) and enumerates what is returned (raw amount, decimals, symbol, human-readable amount). It also explicitly distinguishes itself from the sibling ink_balance by naming the native-coin case as out of scope.

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 an explicit when-to-use ('check stablecoin or token holdings before a transfer or trade') and an explicit alternative ('for the native coin use ink_balance'). The routing decision between sibling balance tools is fully resolvable from the description alone.

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