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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond them: the data comes from an indexer (implying indexed/lagging rather than direct chain state) and results are paged via pageToken, which the agent must know to iterate.

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 with the purpose front-loaded, followed by the returned field list and pagination note. No filler, no restatement of the title or name.

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, listing the returned fields (collection, name, token id, contract, standard, image) is valuable and largely compensates. Remaining gaps are minor: no note on whether results are exhaustive, how ENS names resolve across the 25 chains, or failure behavior.

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 coverage is 75% (address, pageSize, pageToken are all described; chain is an enum). The description only reinforces pageToken ('Paged via pageToken') and implicitly chain; it adds essentially nothing about pageSize or address format beyond the schema. Baseline 3 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?

States a specific verb+resource (NFTs owned by an address on a chain) and enumerates the returned fields, so the agent can immediately distinguish this from getBalances or getTokenHolders. It does not explicitly name or contrast any sibling, which is the only thing separating 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?

There is no guidance on when to use this versus siblings like getTokenHolders, getWalletActivity, or getBalances, nor any stated prerequisites or exclusions. The 'via the Ankr Advanced API indexer' phrase hints at a data source but does not tell the agent when that source is appropriate.

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