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

Annotations already declare readOnlyHint=true, and the description adds valuable behavioral context: the score is annual, z-scored against a trailing decade, updates weekly, and includes fields like trend, z_score, and top_partners. It does not contradict annotations and provides meaningful detail beyond the structured data.

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 two sentences and front-loaded with the primary return value. The first sentence is dense but efficient, packing methodology and output fields. The second sentence gives concrete usage triggers. It is concise and every sentence contributes, though the first sentence could be slightly restructured for readability.

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 no output schema, the description compensates by listing the return fields (trend, z_score, latest_hhi_0_10000, latest_total_imports_usd, top_partners) and explaining the score's meaning and update frequency. It also documents the optional history parameter via the schema. It does not explain the 'trend' semantics in detail, but overall it is adequate for a tool with one optional parameter and safe read-only annotations.

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?

The input schema covers the single optional 'days' parameter fully with a description of its behavior, including the Gold tier requirement for history. The tool description itself does not add extra parameter semantics beyond what the schema already provides. With 100% schema coverage, the baseline of 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?

The description opens with a clear action ('Returns') and specifies the exact resource: a 0-100 US battery-import concentration score. It details the methodology (Herfindahl index of HS 8507 imports z-scored against the trailing decade) and lists output fields, making the tool's function unmistakable and distinct from the many sibling adw 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?

The description explicitly states when to call the tool: 'Call when the user asks about battery supply-chain risk, single-source dependence, or EV/grid-storage sourcing fragility, or when timing supplier-diversification, offtake, or inventory-hedging decisions.' This gives clear context, but it does not mention exclusions or alternative sibling tools, so it falls just short of a 5.

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