Calculate mortgage payment (local)

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

Description adds value beyond annotations (readOnlyHint, idempotentHint) by explaining no network call, deterministic behavior, and PMI applicability. No contradiction.

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?

Four focused sentences, each providing essential information. Front-loaded with purpose, no fluff.

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 all key behaviors and parameters despite 10 parameters and no output schema. Could mention default loan term, but schema already provides default.

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 40%, but description clarifies relationships (down_payment vs. percent, property tax options, PMI condition). Compensates well for missing schema descriptions.

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?

Clearly states it is a local mortgage calculator returning a full PITI breakdown. Distinct from all sibling tools, which focus on property searches, market reports, etc.

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 notes it is deterministic and safe for scenario comparison without network calls. Does not state when to avoid use, but context is sufficient for selection as the only mortgage tool.

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