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

Annotations declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description goes further by disclosing the supported chain set, address formats, the shape of the return payload, a concrete example response, and even per-call pricing — useful context beyond structured fields. Minor gaps remain (no pagination or rate-limit behavior), but disclosure is strong.

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?

Well front-loaded: purpose first, then usage routing, then return shape, then price. The example response and pricing line are somewhat bulky, but each block is scannable and earns its place for a tool with no output schema.

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 stating the return format (symbol, amount) and giving a full example response. Chain coverage, address formats, and exclusions are all present, so an agent has everything needed to call it correctly.

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 description coverage is 100% and both parameters are documented there, including the 'Ethereum 0x... or Stellar G...' format hint that the description repeats verbatim. The only marginal addition is 'no other chains', which the enum already encodes, so the description adds little beyond the schema baseline.

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 (get) and resource (token balances) with explicit scope: Ethereum or Stellar wallet addresses only. It distinguishes itself from sibling tools by naming token_price, token_market_data, and whale_activity as the wrong fit for this use case.

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?

Contains explicit 'Use when' and 'Not for' sections that name the alternative siblings (token_price / token_market_data for price data, whale_activity for cross-wallet transfers). The routing decision is fully specified with no inference required.

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