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

The annotations already mark it as read-only and non-destructive, and the description adds important behavioral detail: USD works without an API key while other currencies return subscription_required with a subscribe link. This helps the agent anticipate authorization outcomes.

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 compact and informational, with no redundant phrasing. Each sentence adds distinct value: what it returns, when to use it, and access behavior.

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?

Given the simple one-parameter interface and the presence of an output schema, the description provides all necessary context: purpose, usage prerequisite, access caveats, and result scope. No important operational detail is 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 single parameter 'currency' is fully described in the schema with a clear ISO code format, case-insensitivity note, and examples. The description also connects it to the access behavior, making its role unambiguous.

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?

States a clear verb ('Return'), a specific resource ('latest stored macroeconomic value'), and a precise scope ('for every available indicator in one currency'). The purpose is immediately understandable and distinct from related tools.

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 tells when to use this tool ('for a compact current macro snapshot') and gives a prerequisite ('after data_catalogue has confirmed the currency coverage'). Also clarifies access conditions for USD versus other currencies.

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