mortgage_calculate_extra_payment

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

The description reinforces the annotations by stating 'No payment is initiated,' clarifying that this is a non-destructive calculation. It also adds context that the projection is 'using mortgage summary data,' indicating reliance on existing data. This goes slightly beyond the readOnlyHint by connecting the behavior to real-world financial safety.

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 two short sentences, front-loaded with the primary purpose and a critical safety note. There is no redundant information, and every word adds value.

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 single-parameter read-only calculator, the description conveys the core behavior and safety. However, it does not mention what the output looks like (no output schema exists), and it lacks details on the parameter's semantics or any prerequisites (e.g., needing to call mortgage_get_summary first). This leaves some ambiguity for the agent.

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 one required parameter, `extraMonthly`, with no description (0% coverage). The tool description does not explain what `extraMonthly` represents or how it impacts the calculation. The agent must rely solely on the parameter name and the tool name to infer its meaning, which is insufficient for a calculation tool.

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 function: projecting payoff acceleration and interest savings. This distinguishes it from sibling tools that handle connection, statements, summaries, and payment history. The verb 'project' and resource 'mortgage summary data' make the purpose specific and unambiguous.

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?

Usage is implied by the description but no explicit guidance is provided on when to use this tool versus alternatives. It does not mention prerequisites like having summary data available or when this would be preferred over mortgage_get_summary or mortgage_get_payment_history.

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