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

Annotations already declare readOnlyHint and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond them: recognition is name-based only and non-listed banks are still convertible because parsing uses layout, not a per-bank template.

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, zero filler. The scope statement leads and the reassuring caveat follows, which is the right ordering for an agent deciding whether to call it.

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 single optional-parameter read tool with annotations covering safety and no output schema, the definition is essentially complete. It only omits the return shape (a plain list of bank names), which is minor given the 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 the baseline is 3, but the description goes beyond it by giving concrete ISO alpha-2 examples (GB, US, ZA) and restating the omit-for-all semantics in the tool's own framing. Marginal but genuine added meaning.

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 and resource ('Lists the banks PivotBank recognises by name') plus the scope dimension (one country or all). No sibling overlap exists among convert_statement/check_statement_balances/summarise_spending, so no differentiation is needed.

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?

Tells the agent the two calling modes (single country vs all) and, more importantly, pre-empts an incorrect use case by stating a statement from an unlisted bank still converts. No explicit when-not for the broader workflow, but the key mis-invocation is ruled out.

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