Calculate mortgage payment (local)

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

Annotations already indicate readOnly and idempotent. Description adds that it is local-only, deterministic, safe, and explains automatic PMI application when LTV > 80%. Does not contradict 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?

Three well-structured sentences: purpose/output, safety/determinism, parameter guidance. No wasted words; fully front-loaded.

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?

Covers main output and key parameter usage. Lacks explicit mention of home_price, interest_rate, hoa_monthly, insurance_annual, and output format. Given complexity and no output schema, it is mostly complete but could be slightly more detailed.

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 low (40%), but description compensates well by explaining mutual exclusivity of down payment fields, defaults, PMI condition, and property tax options. Adds significant meaning beyond schema.

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 it is a mortgage payment calculator, specifies the output (PITI breakdown, total interest), and distinguishes itself from siblings by emphasizing local-only, no network call, and safe for scenario comparison.

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?

Provides clear guidance on parameter alternatives (down_payment vs down_payment_percent, property tax options) and highlights safe use for scenario comparison. Lacks explicit comparison to sibling calculators but gives enough context for effective use.

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