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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses the paid nature ($0.005), the response fields (source citation, effective date, last-confirmed date, staleness flag), and the x402 payment alternative. This is substantive, though it does not mention rate limits or error 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?

Two concise sentences, front-loaded with the essential cost and purpose, followed by response details and payment instructions. Every clause adds value without redundancy.

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?

The description covers the key contextual facets: cost, payment, response content, and staleness behavior. It does not explicitly mention the required 'country' parameter or output format, but the schema covers country and the response fields are enumerated. For a simple look-up tool, this is sufficiently complete.

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 description coverage is 100%, so the baseline is 3. The description adds the series examples, but these are already present in the schema's series description. It does not clarify the country parameter further or add new parameter semantics beyond what schema provides.

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 clearly states the tool returns the current value of a reference series, with concrete examples (policy-rate, vat, minimum-wage), distinguishing it from sibling tools like get_series_history and list_series. The verb and resource are specific and unambiguous.

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?

No guidance is given on when to use this tool versus siblings such as get_series_history or list_series. The description provides parameter examples but no selection criteria or exclusions, leaving the agent without context for choosing among related tools.

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