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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond those annotations: the call is paid, costs $0.001 USDC, supports at most 25 addresses, and is byte-identical to a specific GET endpoint. No contradiction with annotations exists.

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?

The description is compact and front-loaded: batching, limit, use case, cost, supported chains, and exact endpoint compatibility are all covered in four short sentences. No sentence is wasted, and the most decision-relevant facts appear first.

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?

For a two-parameter batch read tool, the description covers everything needed to call it correctly: address limit, required chain selector, eligible chains, cost, and exact request shape. An output schema is present, so return-value documentation is not the description's responsibility.

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 both chain and addresses are already documented in the schema. The description mostly repeats the chain list and 25-address limit, though the example URL does illustrate exact comma-separated formatting. This is helpful but not a substantial semantic addition beyond the schema.

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 clearly states that this is a batch native-balance lookup supporting up to 25 addresses in one call, and the title 'Batch native balances' reinforces the resource. It also distinguishes itself from single lookups by emphasizing batching and lower cost. The byte-identical endpoint reference makes the operation unambiguous.

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?

The description gives clear context for when this tool fits—portfolio and risk bot use cases needing many balances at once—and frames it as cheaper than 25 single lookups. It stops short of explicitly naming an exact alternative like chain_balance or stating a threshold for when to use the singular tool, so it earns a 4 rather than a 5.

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