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

Annotations already declare readOnly=true, idempotent=true, destructive=false, so safety needs no restating. The description adds real value by disclosing the computed outputs (including DSCR and break-even occupancy, which a caller could not guess from the name) and by implying a defaulted model rather than a data fetch. It does not spell out the assumption set behind those metrics, which keeps it below 5.

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?

Two compact sentences front-load the outputs and place the sibling routing second, which is the right order. The trailing marketing URL is not essential to invocation and is the only wasted element.

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?

With no output schema, the description compensates by naming the returned metrics, so an agent knows what a call yields. For a stateless 8-parameter calculator with full annotation coverage, that is nearly sufficient; only the modeling assumptions (e.g. how vacancy and operating expenses feed NOI) are left implicit.

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% with defaults and ranges documented for all 8 parameters, so the schema carries parameter meaning fully. The description names conceptual inputs (NOI, mortgage payment) but adds no syntax, units, or interaction detail beyond the schema — baseline 3.

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?

Names the resource (leveraged rental property returns) and enumerates exactly which metrics are produced: mortgage payment, NOI, annual cash flow, cash on cash return, DSCR, break-even occupancy. It also explicitly positions itself against the sibling cap_rate, so an agent can separate the two without opening either schema.

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?

"Use cap_rate for an unlevered view of the same property" gives an explicit alternative plus the condition that selects it, which is the key routing decision here. It does not cover other plausible alternatives (irr, xirr, moic) or state when a leveraged analysis is inappropriate, so it falls short of a full 5.

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