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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is settled and the description does not need to repeat it. In exchange it discloses what is actually modeled — CMHC insurance in the mortgage, ownership costs, vacancy-adjusted rent, an income-tax estimate option, and qualification with/without rental add-back — which is real behavioral context. It does not say whether results are illustrative estimates or how provincial rules change the math.

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?

A single dense sentence that front-loads the core scenario before listing outputs. Every clause maps to a distinct output dimension, so nothing is filler, though the parenthetical strategy list and the colons make it slightly harder to scan than a short multi-sentence structure would be.

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 17-parameter calculator with no output schema, the description does the important job of telling the agent what comes back: cost comparison, vacancy-adjusted rent, CMHC-inclusive mortgage, and qualification income. It omits how optional inputs like province, marginalTaxRatePct, and equivalentRentMonthly shape the result, but the fully documented schema covers those, leaving no blocking gap.

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% across all 17 parameters, including enums for strategy and province and the 25/30 amortization constraint, so the schema carries parameter meaning and the baseline is 3. The description adds conceptual framing (rent after vacancy, rental add-back qualification) but no parameter-specific guidance beyond what the schema already states.

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 names a concrete scenario (live in one unit, rent the rest) and enumerates the outputs produced: CMHC mortgage, ownership costs, post-vacancy rent, true monthly cost vs renting, and qualification income with and without rental add-back. That is clearly a house-hacking analysis tool, not a generic mortgage or rent-vs-buy calculator. It stops short of naming sibling tools such as rent_vs_buy or mortgage_qualifier to draw the boundary explicitly.

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 only implied by the enumerated outputs — an agent can infer this is for owner-occupied multi-unit purchases, especially with CMHC and rental add-back qualification. There is no explicit when-to-use statement, no exclusions (e.g. not for pure investment properties, not for single-family non-rented homes), and no routing to rent_vs_buy or mortgage_qualifier for simpler cases.

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