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

Adds meaningful context beyond the read-only annotations: it discloses that the data is 'as the bank last reported them (as_of)' and that unreported fields are 'left out, not zero.' The latter is an important quirk that helps the agent interpret results. It does not discuss rate limits or auth, but for a read-only lookup this is solid.

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?

A single dense sentence that front-loads the return payload, followed by two short routing/clarification clauses. Every clause earns its place, though the field enumeration is long.

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?

For a read-only, no-output-schema fetch with one optional parameter, the description tells the agent what fields come back, where related data lives, and how missing values are represented. It is complete enough to call correctly, missing only return-shape/pagination nuance.

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% and the single parameter ('company', with Personal/all semantics) is fully documented there. The description adds no new parameter details, so the baseline 3 applies – the schema carries the parameter burden.

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+resource (returns credit card and loan terms) and enumerates the exact fields returned. It also delineates scope by telling the agent where current balances (list_accounts) and upcoming minimum payments (list_upcoming) live, distinguishing it from those siblings.

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?

Explicitly routes the agent to list_accounts for current balances and list_upcoming for upcoming minimum payments, which is clear 'for X use Y' guidance. It does not state exclusions or when not to call it, but the field-level scope makes its purpose unambiguous.

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