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

Annotations already declare the tool as read-only and idempotent. The description adds valuable behavioral context beyond this, including the payment requirement ('$0.50 USDC via GET /api/esg/{commodity} using x402 on Base') and data sources (ICMM, IEA, Ecoinvent). It does not fully clarify the distinction between preview and full data, as the title 'ESG profile preview' implies a free tier, but the description only mentions payment for 'full data'. This ambiguity prevents a perfect score.

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 composed of three focused sentences, each adding new information: the core functionality and outputs, the target audience, and the payment/access details. There is no redundancy or filler, and key information is front-loaded.

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 simplicity (one parameter), the presence of annotations (read-only, idempotent) and an output schema, the description is largely complete. It covers purpose, outputs, audience, and cost. However, it leaves ambiguity regarding whether a free preview exists without payment and what the output structure is, though the output schema handles the latter. The payment/preview clarification would make it fully complete.

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 fully documents the only parameter 'commodity' with an enum of 20 values and a description ('Mineral commodity slug'). The description adds minimal extra parameter semantics, just noting 'all 20 commodities' without detailing slug formats or validation rules. Since schema coverage is 100%, the baseline score 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 clearly states the tool's function with a specific verb ('Returns') and defines the resource scope ('ESG intelligence for critical minerals'), enumerating concrete outputs (recycling metrics, carbon intensity, regulatory exposure). This distinct functionality differentiates it from sibling tools like supply_resilience or criticality.crosscheck, which focus on other aspects.

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 identifies the primary use case: 'Sustainability analysts, compliance officers, and carbon-accounting agents use this for ESG due diligence.' This provides clear context for when to use the tool. However, it does not explicitly state alternatives or when not to use it, which would elevate the score to 5.

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