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

Goes well beyond the read-only annotation: discloses that formulas are standard, any currency is accepted, and no external price/rent lookup occurs, plus cost ($0.002 USDC via x402, failures not charged). Minor friction with openWorldHint=true given the claim of no external data lookups, but that hint is loosely defined and it is not a direct contradiction of readOnlyHint.

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?

Front-loads the purpose and metric list, then assumptions, then alternatives, then price — a sensible order. The metric enumeration and related-tools sentence are long but each earns its place; only slight trimming would be possible.

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?

An output schema covers return values and annotations cover the read-only profile, so the remaining gaps are assumptions and cost — both addressed ('standard formulas', 'any currency', no lookups, per-call price). An agent has everything needed to call it correctly.

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 100% and every parameter carries its own description and default, so the schema does the work. The description's list of computed metrics implies which inputs matter but adds no per-parameter meaning (units, string-encoded numbers, rounding) beyond the 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?

States a specific verb+resource ('Rental property investment calculator from your numbers') and enumerates exactly what it computes (cap rate, DSCR, cash-on-cash, break-even occupancy, 1% rule). Explicitly separates itself from the listing-lookup siblings by saying it does not look up prices or rents.

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?

Gives the key selection condition ('from your numbers' / 'does not look up prices or rents') and names two alternatives with the need each serves (Bien'ici for French ads, Crexi for commercial listings). Lacks an explicit statement of when not to use it, e.g. for financing-rate lookups where bankrate_mortgage_rates would apply.

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