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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral context beyond that: the returned payload (holder address with balance, total holder count, token decimals) and pagination behavior ('Paged via pageToken'). It does not mention rate limits or indexer staleness, but the added disclosure is meaningful.

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?

A single dense sentence front-loaded with the resource, then return fields, then pagination; nothing is wasted. It is slightly packed but 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?

With no output schema, the description carries return-value duty and does so by listing the payload fields, and it covers pagination for a paged endpoint. The only gap is the lack of any hint about ordering or limits on how holders are ranked, which for a read-only indexed query is a minor omission.

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 75%, with pageSize, pageToken and contractAddress documented inline, and chain self-documenting via a 25-value enum. The description only echoes pageToken for pagination and adds no syntax or constraints beyond the schema, so the baseline 3 for high coverage is appropriate.

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?

The description states a specific resource (holders of an ERC-20 token contract on a chain) and even names the backing indexer, so an agent knows exactly what it retrieves. It does not explicitly differentiate itself from siblings like getBalances or getWalletActivity, but the resource is distinctive enough to be inferred.

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?

There is no when-to-use guidance and no mention of alternatives; the agent is left to infer that this tool is for enumerating token holders rather than for account balances (getBalances) or transfers (getLogs). Pagination is noted, but no conditions for picking this tool over siblings are given.

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