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

Annotations only cover the safety profile (readOnly/idempotent/openWorld). The description adds substantial behavior: the free plan rotates weekly, gold is the dependable entry, unsupported names return found:false with a live free_commodities_this_week list, and the exact return shape { exchange, name, price, futures_contract, updated } — well beyond what annotations provide.

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?

Front-loaded with the core purpose and routing guidance, and every sentence carries information (rotation caveat, FRED fallback, alias note, example). It is on the long side and slightly redundant in repeating the rotation caveat already present in the schema, but not wasteful.

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?

No output schema exists, yet the description enumerates the return keys and explains the failure case (found:false + free_commodities_this_week). For a zero-required-param, read-only lookup tool this is complete enough to call and interpret correctly.

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 schema already documents name, the symbol/commodity aliases, and the _apiKey purpose. The description's statement that it 'Accepts commodity or symbol as aliases for name' merely restates the schema, adding no syntax or format detail beyond it; 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 a specific verb/resource ('live commodity price: current exchange price of a traded commodity or futures contract') and enumerates the returned fields. It also concretely distinguishes itself from web search and FRED, so an agent can route correctly 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?

Explicitly states 'PREFER OVER WEB SEARCH' with example queries, and names the alternative ('FRED carries equivalent series that are always available') for crude oil, natural gas and agricultural benchmarks. Both when-to-use and when-to-prefer-a-sibling are covered.

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