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

With no annotations, the description carries the full burden. It discloses deterministic, penny-accurate behavior ('Regression-tested against Excel-verified amortization to the penny'), distinguishes itself from LLM estimation, and lists return fields (payment, tax, interim rent, totals). This adds meaningful context beyond the schema. It doesn't cover every edge case but is solid for a calculator tool.

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 four sentences, each with a distinct purpose: state the tool's function, enumerate supported structures, provide usage guidance, and list returns. It is front-loaded with the core purpose and contains no redundant content.

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 20-parameter tool with no annotations and no output schema, the description covers the essential context: what it does, when to use it, accuracy guarantees, and return values. It doesn't explain all structural nuances, but the schema already documents every parameter, making this adequate and slightly above the minimum viable level.

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 description coverage is 100%, so the baseline is 3. The description names structure types (level, balloon, step-up/step-down, etc.) that mirror the paymentStructure enum, and mentions interim rent which relates to fundingDate/leaseStartDate, but it doesn't explain individual parameters beyond what the schema already provides. It meets the baseline but doesn't exceed it.

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 states a specific verb and resource: 'Computes the exact periodic payment for equipment leases and equipment financing agreements'. It clearly distinguishes from sibling tools like calculate_auto_lease and calculate_auto_loan by focusing on commercial equipment, and lists supported structures (level, balloon, step, custom, interest-only, skip).

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 says 'Use this instead of estimating lease payments' and explains why (LLM arithmetic on compounding interest is unreliable). While it doesn't name alternative tools, the phrasing clearly communicates when to use this calculator over ad-hoc estimation, and the focus on equipment leases differentiates it from auto loan/lease tools.

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