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

Annotations already convey read-only and non-destructive behavior, and the description adds valuable context beyond them: it requires an FXMacroData API key and anonymous calls return subscription_required with a subscribe link. This meaningfully informs the agent about authentication-dependent behavior.

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 short sentences, each adding distinct value: what the tool returns, how it relates to commodities, and access requirements. The main behavior is front-loaded with no filler.

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 zero-parameter read-only batch tool with an output schema, this description covers the necessary ground: result scope, sibling relationship, and authentication behavior. There are no missing operational details an agent would need before calling it.

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?

There are zero parameters, so the input schema is trivially complete and there is nothing for the description to clarify. The description's mention of returning all indicators in one response also implicitly explains why no parameters are needed.

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 verb ('Return'), a clear resource ('latest stored value for every available commodity indicator'), and one-response batch behavior. It also names 'commodities' as its single-tool counterpart, which distinguishes it from siblings.

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 frames this as the batch counterpart to commodities and notes that it is a subscriber tool, implying when it should be used. It does not explicitly say 'use commodities for a single indicator,' but the batch-versus-single distinction provides solid routing guidance.

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