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

With no annotations, the description carries the disclosure burden. It transparently states the $0.005 cost, the x402 payment path, and key return attributes (official source, effective date, last-confirmed date, staleness flag). It does not describe error cases or pagination, which are secondary for a single-value retrieval.

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 sentences, packed with essential information: cost, purpose, examples, return attributes, and auth. Zero filler, well front-loaded.

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 simple current-value lookup with no output schema, the description sufficiently explains what the response contains and how to access paid data. It could mention the historical alternative or list all series, but sibling tool names imply these. Overall adequate and complete for the tool's simplicity.

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 parameters are already well documented. The description adds example series IDs and mentions api_key as an alternative to x402, but does not add deep semantic detail beyond the schema. Baseline 3 is appropriate.

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). It distinguishes itself from siblings like get_series_history and list_series by emphasizing 'current' and the specific series format.

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?

It clearly indicates this is for fetching current values, and mentions the payment/auth flow. However, it does not explicitly say when to use get_series_history or other alternatives, relying on the 'current' qualifier and sibling names to convey the distinction.

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