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

The description fully discloses the tool's behavior: it calculates utilization before/after, shows whether the limit leaving the denominator, and indicates if utilization crosses a band upward. It also states it does not make payments or change accounts, aligning with the readOnlyHint and destructiveHint annotations. No contradiction with 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 well-structured and succinct despite covering many nuances. It packs a lot of information into a compact space, using clear clauses and examples. The repetition of what it does not do is purposeful for emphasis and does not feel verbose.

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 the tool's complexity (multiple card parameters, optional inputs, behavioral edge cases), the description covers all necessary context. It explains the role of each key parameter, the output of the calculation, and the tool's non-destructive nature. The presence of an output schema further reduces the need for description-level output details.

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?

The schema has 100% description coverage, but the tool description adds crucial semantic details beyond the schema: cardName supports partial matching, today's date should be passed to avoid UTC fallback, and APR 0 means a real interest-free rate, not unknown. These clarifications enhance parameter understanding.

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 states the tool's purpose: to answer questions about cancelling, downgrading, or consolidating cards by explaining utilization impact. It also explicitly says what it does not do (does not close, cancel, or change cards), leaving no ambiguity about its scope.

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 provides concrete guidance on when to use the tool (questions about cancelling/downgrading/consolidating), how to provide card data (optional, with examples of naming), and what happens if no cards are supplied. It also warns against passing 0 for unknown APR or minimum payment, which is critical for accurate estimates.

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