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

Annotations only declare readOnlyHint and openWorldHint; the description adds substantial context beyond that: a per-call price of $0.002 in USDC via x402, accepted chains (Base, Solana, Arc), and the crucial fact that failed calls are not charged. It also discloses the data range (latest value plus up to 24 months). This is exactly the extra behavioral detail annotations cannot carry.

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?

Purpose is front-loaded and each sentence carries information (source, disambiguation, range, cost). The payment detail is correctly placed last, though the disambiguation clause could be folded tighter to avoid slight redundancy with the name.

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 single-parameter read with an output schema and covered annotations, the description is nearly complete: source, units, history window, cost, and a name caveat are all present. The only missing piece is explicit routing versus sibling agri-price tools.

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%, so the single 'months' parameter and its 1–24 range/default are already fully documented. The description only echoes 'up to 24 months of history', adding marginal confirmation rather than new meaning, so the baseline 3 applies.

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?

Names the specific resource (coffee, sugar, cocoa), the exact nature of the data (monthly world reference prices from FRED / World Bank, USD), and explicitly disambiguates the misleading 'ice' name by stating these are not ICE futures settlements. An agent can tell this apart from related agri tools without opening the schema.

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 gives a clear negative: 'not ICE futures settlements', which steers the agent away from a wrong expectation. However, it never names or contrasts the obvious alternatives in the sibling list (energy_cme_agri_spot_futures, energy_fao_food_price_index), so the positive when-to-use condition is left to inference.

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