wallet_balance

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description nonetheless adds real context the annotations cannot: it is free, requires no API key, nothing is signed or spent, and it fails with an error on unknown symbols or unreachable upstreams. It stops short of describing pagination or rate limits, but for a read-only public lookup this 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?

Front-loads purpose, then blocks for usage, return shape, example and cost. Every section earns its place, though the literal example response is somewhat verbose for a two-parameter lookup.

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, so the description compensates by describing the return shape ('list of token balances (symbol, amount)') and giving a concrete example response. Combined with the explicit chain restriction and error behavior, 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%, so both parameters are already documented with the 0x…/G… format hints in the schema itself. The description usefully reinforces that no chains other than Ethereum and Stellar are supported, but adds little syntax beyond the schema, so the baseline of 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 ('Get the token balances for any Ethereum or Stellar wallet address') with the scope of chains bounded. It explicitly distinguishes itself from token_price/token_market_data and whale_activity, so an agent can select it without opening any 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?

Provides a 'Use when' line and a 'Not for' line that names the specific alternative tools (token_price, token_market_data, whale_activity) and the condition that routes to each. Nothing about when-not-to-use 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.