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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is covered. The description adds one genuine behavioral fact – that it calls only this single endpoint and returns that response verbatim – but says nothing about pagination behavior, rate limits, or response size despite the 1000-entry default limit.

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?

Three compact sentences with the scope constraint front-loaded before the capability list. The opening 'Token Balances.' is a verbatim restatement of the title and earns nothing, but the remaining text is efficient.

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 an output schema present, the description needn't explain return shape, and 100% schema coverage plus full annotations cover the mechanics. What remains thin is differentiation from the batch and history siblings, which is the only thing an agent could plausibly get wrong here.

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 all 11 parameters including the sortByAsc/sortByDesc exclusivity and the minAssetValue/maxAssetValue override behavior are already documented in structured data. The description adds no parameter-level meaning beyond what the schema provides, so 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 ('fetching wallet token balances') and names the exact endpoint GET /v4/wallets/{ownerAddress}/token-balance, plus enumerates the asset types returned (SPL, Token-2022, USD values, staking balances). It never names a sibling, so the agent must infer the difference from get-token-balances-batch or get-wallet-token-balance-history, which keeps it from a 5.

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?

Usage is only implied: 'for fetching wallet token balances' tells the agent what class of task it fits, but there is no explicit when-to-use, no exclusions, and no routing to the batch or history variants in a sibling list that contains three closely related balance tools. Given the crowded sibling set, this is a real gap.

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