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

Annotations only cover readOnly/openWorld; the description adds genuinely non-obvious behavior: $0.002 USDC per successful call, x402 payment across Base/Solana/Arc, and failed calls are free. It also discloses the upstream data ceiling (GoPlus top-10 only), which caps what the tool can answer — an important behavioral caveat.

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-loaded with the core metric list, then limits, then pricing — logical ordering with no filler. The parenthetical chain list is mildly redundant with the schema but serves as a quick scan aid.

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 need not explain return shapes, yet it summarizes them anyway; parameters are fully covered by the schema, and cost, payment rail, billing behavior, and data-source limits are all disclosed. An agent has everything needed to decide and call 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 coverage is 100% and both parameters (chain enum values, 0x address format, ethereum default) are already documented in the schema. The description restates the supported chains but adds no syntax or semantics 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?

The description names the resource (holder concentration for an EVM token) and enumerates exactly what it returns: top-1/3/10 supply share, total holder count, and contract share of the top 10. It does not steer the agent away from related siblings such as anti_whale_limit_detector or token_composite_safety_score, so it stops short of 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 implied by the metric list and the EVM-only scope, and the 'top-20 view and funding-source clustering are NOT provided' line functions as a partial when-not. However, no alternative tool is named for those use cases, so the agent must infer routing on its own.

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