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

With no annotations, the description carries the full behavioral burden, and it does disclose the return contents (code, name, IBAN length) for what is evidently a read-only lookup. However it says nothing about whether the list is static or dynamic, its size, ordering, or caching behavior. Adequate but with gaps for an annotation-free tool.

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?

A single front-loaded sentence with no filler; the resource and its return shape are stated immediately and nothing is redundant.

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?

No output schema exists, so the description usefully names the return fields (code, name, IBAN length). For a zero-parameter, low-complexity lookup this is nearly sufficient; only the absence of any indication of list size or stability keeps it from a 5.

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 per the baseline this scores 4. The description adds no parameter detail, and none is needed.

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?

States a specific verb+resource ('List all countries') and adds scope ('supported for IBAN generation') plus the returned fields, which clearly separates it from generate_iban and validate_iban. It stops short of naming those siblings explicitly, so 4 rather than 5.

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 phrase 'supported for IBAN generation' implies the context in which an agent would need this list, but there is no explicit when-to-use statement, no exclusions, and no named alternatives. Usage is only inferable from the surrounding IBAN tools.

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