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

With no annotations provided, the description carries the full behavioral burden and does so thoroughly. It discloses the $0.005 cost, the x402 payment/auth flow, response contents (official source citation, effective date, last-confirmed date, staleness flag), and the risk that later gazettes can silently retire the value. This is far richer than a typical read-hint.

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 dense but tightly organized: it front-loads the paid/current-value identity, then adds only decision-relevant details about response fields, payment path, and follow-up actions. Every sentence earns its place and there is no repetition of schema content.

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 paid tool with no output schema and no annotations, the description covers cost, authentication, return-value semantics, and required post-call follow-up. Required parameters are already fully documented in the schema, so nothing needed to invoke the tool correctly 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 schema already documents all three parameters at 100% coverage, so the baseline is 3. The description adds real value by giving valid series examples and explaining api_key's behavioral effect (bypasses x402, metered for invoicing), which goes beyond what the schema states.

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 opens with a specific verb and resource: 'Current value of a reference series', with concrete examples like policy-rate, vat, and minimum-wage. The 'current' qualifier helps distinguish it from get_series_history, and the mention of get_changes clarifies its downstream role, though it does not explicitly contrast all sibling 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?

The description clearly sets the call context: the tool is paid, api_key bypasses x402, and after a 200 the agent should bind get_changes or register_alert to avoid silent retirement. It does not explicitly state when to prefer this over get_series_history or list_series, but the current-value framing provides enough practical guidance.

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