get_available_balance

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds the dependency on get_accounts_and_cards and the shape of the returned figures, but no auth requirements, rate limits, or caching/freshness behavior.

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 sentences, zero filler, and the core purpose plus return contents are front-loaded before the prerequisite note. Every sentence carries distinct 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?

With no output schema, the description usefully enumerates the returned balance fields and covers the required-argument dependency, which is what an agent needs to call it. Minor gaps remain around error cases (invalid productId, mismatched productType) but the definition is otherwise sufficient for a simple read tool.

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 100%, and the schema already explains productId sourcing from get_accounts_and_cards as well as the CARD/ACCOUNT enum and its default. The description only restates that the product is a card or account, so it adds nothing beyond the structured fields — baseline 3.

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 verb and resource ('Get detailed balance breakdown for a specific card or account') and enumerates the returned fields (balance, available balance, frozen balance, offline available). It is clearly distinct from transaction- and event-oriented siblings, though it never names an alternative explicitly.

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 gives a concrete prerequisite flow: 'Use get_accounts_and_cards first to find the product ID,' which tells the agent how to obtain the required argument. It stops short of stating when not to use this tool or which sibling to prefer for other balance-like queries.

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