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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the description adds real value by disclosing the $0.01 USDC charge on Base and that invalid ids return 404 with no charge. The one gap is the payment mechanism itself — whether settlement is automatic or requires a signature — which is the biggest unknown for a paid tool.

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?

Four short sentences with no filler. The cost note is front-loaded ahead of the purpose statement, which is defensible for a paid tool but slightly delays what the tool actually returns.

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 covering return shape, one fully documented enum parameter, and complete safety annotations, the description fills the remaining gaps: price, valid ids, and error/no-charge behavior. Only the settlement mechanics and the get_cpi overlap are left unresolved.

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 the enum already constrains id to NFP/GDP/CPI, so restating the same three ids adds no meaning. The "others return 404 (no charge)" note is the only marginal addition and is somewhat at odds with an enum that makes other values unrepresentable.

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?

States a specific verb and resource: fetch the latest US CPI, nonfarm payrolls, or GDP release as cited items with the official source. It names the sibling it is not in one respect (sample_macro is the free version), but it never clarifies its relationship to the get_cpi sibling, which plausibly overlaps with the CPI id.

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?

"Call when you need the latest US CPI, nonfarm payrolls or GDP release as cited items with the official source" gives a clear use condition, and "Free: sample_macro" routes cost-sensitive callers to the alternative. It stops short of stating when to prefer get_cpi or get_bundle instead.

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