lookup_bank

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

With no annotations provided, the description carries the burden but does well by stating the input format and the exact return fields (name/kana/hiragana/romaji). The read-only nature is implied by 'look up', and no side effects or hidden behaviors are plausible for a simple lookup. It does not explicitly state 'read-only' or error handling, but for this tool the disclosure is sufficient.

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, no filler, and the key information is front-loaded. Every word adds value, making it an exemplary concise description.

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?

The tool is simple with one parameter and an existing output schema, so the description covers all necessary context: what input is needed, how to format it, and what will be returned. No further behavioral details are required for this use case.

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 0%, so the description must compensate for the sole parameter. It does so explicitly: '4-digit zengin bank code (統一金融機関コード)' provides both the format and domain meaning, going well beyond the bare schema property.

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 uses a specific verb ('look up') and resource ('Japanese bank') with a defined key ('4-digit zengin bank code'), clearly distinguishing from sibling tools like search_banks (which implies searching) and lookup_branch (which targets branches). It also lists the output fields, making the purpose unambiguous.

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 clearly implies the use case: when you have a 4-digit bank code and need bank details. However, it does not explicitly contrast with search_banks or state when not to use this tool, so it falls short of a 5 but is still contextually clear.

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