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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: the data is manually collected one bank at a time from bank websites, which signals a curated, potentially incomplete snapshot, and it states what each record contains.

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 dense sentences, zero filler, with the core scope and data provenance front-loaded and the parameter behavior stated last. Every clause carries information.

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?

There is no output schema, and the description compensates by describing both possible return shapes and the fields within a record. For a single optional-parameter read tool, nothing an agent needs to call 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?

Schema coverage is 100%, so the country code's ISO 3166-1 alpha-2 format is already documented. The description adds real semantic value by explaining how presence versus absence of the parameter changes the result shape (per-bank records vs per-country counts), which the schema does not convey.

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 names a specific resource (cash bonuses for opening a personal current account) and a precise scope (the 27 EU countries), plus the fields returned (amount, deadline, source page). It is clearly distinguishable from the sibling tools, which cover Polish savings bonds and retail government bonds rather than EU current-account bonuses.

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 explicitly explains the two usage modes: supply a country code for a full bank-by-bank list, omit it for per-country counts. That is clear operational context, but no alternative tool or exclusion is named, and there is no guidance on when the aggregate mode is preferable over the detailed mode.

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