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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds one genuinely useful caveat — 'Only some countries have a bank list' — implying possible empty or unsupported results. It says nothing about what happens for an unsupported country or what the response contains, leaving the main behavioral question unanswered.

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?

Three short sentences, front-loaded with the core purpose and followed by usage and a caveat. No padding, though the final caveat sentence is placed where a parameter note would have been more valuable.

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?

With no output schema and zero parameter documentation, the description should at minimum explain the country/currency inputs and what a returned bank entry looks like. It covers purpose and one caveat adequately but leaves the agent guessing about the currency parameter's effect and about failure modes for unsupported countries.

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 description coverage is 0%, so the description carries the full burden for both parameters, yet neither is mentioned. The description never says that 'country' is a required two-letter code or what the optional 'currency' parameter changes about the result set, which is the one thing an agent could easily get wrong here.

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 a bank payout can reach in a country' — and adds the alias detail, so an agent knows this is a bank directory lookup rather than a payout options list. It doesn't explicitly contrast itself with nearby siblings such as get_payout_options or get_supported_countries, which keeps it below a 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?

'Use it when someone asks whether a particular bank is supported' gives a concrete triggering scenario, which is stronger than most definitions. It names no exclusions or alternative tools, so the agent is not told what to call instead when the question is about payout methods generally.

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