List covered central banks & tax authorities

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

Annotations cover the read-only and open-world hints, and the description goes beyond them with auth context ('No API key needed') — a real distinction from the sibling get_rates_authenticated — plus freshness/health metadata ('whether it is behind schedule'). That is exactly the kind of operational context annotations cannot express.

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 call-first instruction is front-loaded, and every subsequent clause carries distinct payload: use cases, inventory size, return fields, and auth requirement. No filler or restatement of the name.

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 zero-parameter list tool with an output schema and read-only annotations, this description covers trigger conditions, inventory scope, field contents, cross-tool linkage, and auth needs. Nothing an agent needs to select or invoke it 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 tool takes zero parameters, so the baseline is 4 and there is no parameter semantics to clarify. The description's field-level explanation (code, name, publication date, schedule status) is informative but describes the response rather than inputs.

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 gives a precise verb+resource ('Returns every covered source — 121 central banks plus 3 tax authorities') and enumerates the exact returned fields (code, name, latest publication date, schedule status). It distinguishes itself from siblings by explicitly linking its `code` output to `get_official_rates`'s `bank` input.

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 opens with an explicit trigger ('Call this FIRST when you need a bank code') and supplies sample user questions ('which central banks do you cover?' / 'do you have rates from X?'), which map intent to this tool. It also names the downstream tool that consumes the result, so the when-to-use path is unambiguous.

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