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

Beyond the readOnly and openWorld annotations, the description discloses the data source, update frequency, and crucial limitations: the values are indexes rather than spot prices and exclude Gulf/Tampa quotes. It also adds important billing behavior, including the per-call cost and the fact that failed calls are not charged.

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 front-loaded with the core data identity, followed by the most important caveat and then pricing. Every sentence adds distinct value, and there is no redundant or filler language.

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 data retrieval tool with an output schema and safety annotations, the description supplies the remaining context an agent needs: the source, the nature of the values, exclusions, and cost. Nothing essential for correct selection or invocation appears to be missing.

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 only parameter, months, is fully documented in the schema with its range and default. The description does not add any parameter-specific semantics, so the schema carries the meaning and the baseline score of 3 is appropriate for high schema coverage.

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 states a specific resource and scope: monthly US producer price indexes for ammonia and nitrogen fertilizer from BLS via FRED. It also distinguishes the data from spot prices by explicitly saying these are index values, not USD spot quotes.

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 clearly signals when not to use the tool by excluding USD spot prices and US Gulf/Tampa spot quotes, which helps route the agent away from spot-price use cases. However, it does not explicitly name alternative tools or spell out the exact conditions under which this tool should be selected over other energy data tools.

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