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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: the $0.001 USDC cost per call and that it is byte-identical to a specific GET endpoint, which conveys exact behavior and response equivalence. No contradiction with annotations.

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 carry high information density with no filler. The primary purpose is front-loaded, followed by cost, chain list, and an exact endpoint equivalence. Every element earns its place, making it efficient and easy to parse.

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?

Given the tool's moderate complexity (3 required params, output schema present, annotations cover safety), the description is complete. It covers purpose, scope (up to 10 tokens, one chain), supported chains, cost, and exact API mapping. No critical information is missing for an agent to call it 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% for the three parameters, each with descriptive text (chain list, holder address, comma list of up to 10 token addresses). The description adds little beyond the schema—it mentions formatting with decimals and symbol for each token, but that's implicit in the output. Baseline 3 is appropriate since the schema handles parameter semantics.

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 the tool performs balanceOf for one address across up to 10 tokens on a single chain, with per-token decimals and symbol formatting. This specific verb+resource distinguishes it from siblings like chain_token_balance (single token) and implies batch behavior, so an agent can readily separate it from similar tools.

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?

It explicitly frames the use case as 'the holding snapshot a portfolio bot wants in a single settlement instead of ten', which suggests when to use it (multi-token balance query on one chain). It doesn't name alternative tools or explicitly say when not to use it, but the context is clear and it lists supported chains, giving enough guidance for selection.

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