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

Annotations already declare readOnlyHint and openWorldHint, so the bar is lower, yet the description adds real value: block pinning, an on-chain delegated-key signature with a verifiable receipt, and an explicit prompt-injection caveat that the result is data, not instructions. It doesn't cover pagination or failure behavior, but this is solid beyond-annotation context.

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-loads the core purpose before the provenance boilerplate, and the return-shape listing is compact. The service-address and receipt phrasing is somewhat verbose but each clause carries functional information.

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?

With no output schema, the description compensates by enumerating the return object's fields (token, address, raw, amount, symbol, decimals, blockPinned). Combined with the trust/verification note, an agent has enough to invoke and interpret the call; only the sibling-selection dimension is unaddressed.

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 schema already documents token, address, and the block parameter including its 'finalized'/'safe'/'latest' enum and default. The description's 'pinned to one block' adds only marginal framing beyond the schema, so the baseline 3 applies.

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 — BEP-20 balance of an address, pinned to one block — with a clear scope (raw and token units). It does not, however, say how it differs from the sibling 'balance' (presumably native-coin) or 'tokenInfo', leaving disambiguation to inference.

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?

No when-to-use or when-not-to-use guidance is given. With siblings like 'balance' and 'tokenInfo' present, the agent gets no help deciding which to call; the only contextual note is that the service is free, which is not selection guidance.

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