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

Annotations already cover read-only and open-world behavior, yet the description still adds real value: a paid-call model ($0.002 USDC per successful call via x402 on Base, Solana or Arc) and the explicit guarantee that failed calls are not charged. It also discloses source and monthly cadence, though it omits refresh latency or rate limits.

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?

Three sentences, front-loaded with the actual data identity before the pricing note and the name-disambiguation caveat. The 'name is kept for the owner's route' clause is slightly inside-baseball but earns its place as a naming warning.

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-optional-param read with an output schema, this covers identity, units, source, cadence, history depth and the payment model. Only minor gaps remain, such as refresh frequency and whether values are nominal USD.

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 single 'months' parameter is fully documented there, including the 1–24 range and default of 3. The description only echoes the 24-month ceiling, adding no new meaning; baseline 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?

Names the specific resource (monthly world reference prices for corn, wheat, soybeans), the source (FRED / World Bank series, USD) and the payload shape (latest value plus up to 24 months of history). It also explicitly negates the misleading tool name by stating these are not CME futures quotes, so an agent can distinguish it from futures-style siblings at a glance.

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 'not CME futures quotes' line implicitly steers an agent away from futures tools, and the data-source disclosure implies when this is the right choice (World Bank reference prices). But there is no explicit when-to-use/when-not-to-use against alternatives such as energy_usda_wasde_crop_reports or energy_ice_coffee_sugar_cocoa, and no prerequisites stated.

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