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

The annotations already cover readOnly, idempotent, and non-destructive behavior. The description adds useful behavioral context beyond that: the tool reports balances from the card account rather than a unified account, defines outstanding as a simple principal minus payments calculation, and notes per-currency grouping. This enriches the agent's understanding of response semantics.

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?

The description is a compact two-sentence definition with no filler. It front-loads the main resource and immediately provides clarifying details in parentheses. 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?

Given an output schema is present, the return structure needs no explanationchedron. The description covers the main content well but falls short on the one input parameter, include_closed, leaving a gap that is significant for correct invocation, especially since the schema itself provides no description.

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?

There is one parameter, include_closed, with 0% schema description coverage, and the description does not mention it at all. The parameter name hints at filtering closed items, but the description provides no clarification of what 'closed' means or what the default behavior is, so the agent must guess.

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 credit cards and loans. The description breaks out exactly what is included for each (card limit, cycle, current balance; loan borrowed/lent, payments, outstanding), distinguishing it clearly from siblings like list_accounts and list_holdings.

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 makes clear what data is covered, so an agent can infer when to call it versus other list tools, but there is no explicit 'when not to use' or reference to alternatives. The usage context is implied by the resource scope, not directly stated.

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