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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description still earns credit by disclosing the sort order and the data caveat that the returned 'balance' already has decimals applied and must not be divided again. It does not cover pagination behavior or rate limits, so it falls short of a 5.

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?

Two sentences with no filler; the resource, ordering and aggregate are front-loaded, and the alternative is deferred to the end where it belongs. Every clause carries 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?

There is no output schema, so the description carries the burden of explaining returns, and it does name the key fields (balance semantics, ordering, holder count). Pagination is handled by the schema, but a token-decimals caveat on the aggregate and any cap on returned holders remain unstated.

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% — chain, pageSize, pageToken and contractAddress are all documented in the schema (including the chain enum hint pointing at listChains). The description adds nothing about parameter syntax or formats, so the baseline 3 is correct; its added value is about returned fields, not inputs.

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 ('who holds an ERC-20 token on one chain'), discloses the result ordering ('largest balance first'), and names the extra aggregate ('total holder count'). It is immediately distinguishable from siblings such as getBalances and getWalletActivity.

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?

Explicitly routes the agent away from this tool: 'For one wallet's tokens use getBalances' names the alternative and the condition that selects it. The when-not rule is stated rather than left to inference.

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