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

Annotations already signal destructiveHint=true, and the description adds the important behavioral detail that the operation 'creates or replaces' the card's terms. This clarifies that existing values may be overwritten. It does not add extraneous behavioral guarantees, but it provides meaningful context beyond the annotations.

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 single well-structured sentence that front-loads the core purpose, lists the relevant terms, and ends with the important upsert behavior. Every phrase earns its place; there is no filler.

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 output schema and annotations reduce some burden, and the description covers the core card-term concepts. Still, apr_percent is left undocumented and the two minimum-due parameters are conflated, so an agent cannot fully infer the semantics of all seven parameters. It is adequate but not complete.

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?

With schema description coverage at only 43%, the description helps by naming credit_limit, statement_day, due_days_after_statement, and minimum due. However, it omits apr_percent entirely and lumps minimum_due_percent and minimum_due_floor together as 'minimum due', leaving ambiguity. It partially compensates for the schema gap but not fully.

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 clearly identifies the operation: giving a card account its terms, with the key fields listed (limit, statement day, days until due, minimum due). It also adds the create-or-replace behavior, which helps distinguish it from plain update tools. It does not explicitly name a sibling for contrast, so it stops short of 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?

The intended use is implied: use this when configuring a card account's terms. There is no explicit 'use when' or 'use instead of' statement, and no guidance about when update_account or set_account_balance would be more appropriate. The context is clear but only by inference.

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