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

With no annotations, the description carries the full behavioral burden. It does disclose that omitting 'country' returns the current table and providing a country code returns that country's history, with examples (us, eu, jp, gb). However, it does not mention output format, data frequency, or other behavioral traits like ordering or completeness.

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 entire description is one tight sentence, front-loading the core resource and scope, then using a colon to explain parameter-dependent behavior. No filler or redundancy; every word earns its place.

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 tool with one optional parameter, no output schema, and no annotations, the description gives the essentials but leaves ambiguity about the exact response shape (e.g., fields in the current table or history series). An agent could call the tool but may not know what data structure to expect, so it is only moderately 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?

The single parameter 'country' is fully explained: it is optional, takes short country codes like us/eu/jp/gb, and its presence switches between table and history modes. This goes far beyond the bare schema (maxLength 4) and gives the agent concrete usage guidance.

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 resource (policy rates) and scope (49 economies), and differentiates its two modes: current table vs. one country's history. It distinguishes itself from sibling tools like funding_rates or macro_series by topic, though it lacks an explicit verb like 'get' or 'list'.

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 implies usage: if you need central bank policy rates, this is the tool. It gives clear context on how to request either the full table or a country's history, but it does not explicitly mention alternatives or when not to use this tool, leaving the agent to infer differentiation from siblings.

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