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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, and the description adds meaningful context on top: the deterministic computation rule, the MAS regulatory basis, and the 'indicative figures, not legal or financial advice' caveat. It stops short of describing the return shape, but for a pure calculation tool this is strong added value.

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-loaded with the action and formula; the joint-application sentence, disclaimer and source attribution each carry a distinct purpose. The 'From Propely (propely.sg)...' sentence is borderline branding but is short and sets provenance.

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?

No output schema exists, but the stated formula lets an agent infer the returned tenure value. All four parameters are covered by the schema plus the description's rule explanation, so nothing needed to call it correctly is missing, though an explicit statement of the return format would complete it.

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%, so the baseline is 3, but the description genuinely adds meaning: it explains that borrower1Age enters the '65 minus age' rule and that the income fields produce an income-weighted average age for joint applications, telling the agent why the numeric parameters matter.

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 and resource ('Work out the longest home loan tenure MAS allows for private residential property in Singapore') and even gives the governing formula, so the agent can tell it apart from siblings like calculate_tdsr or calculate_absd without opening a 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?

It clarifies the joint-application path ('also give the second borrower', income-weighted average age), which is useful context, but it never says when to prefer this over the other loan-related siblings (calculate_tdsr) or states any exclusion. Usage is implied rather than explicit.

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