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

Annotations already declare readOnlyHint/idempotentHint, so safety is covered. The description adds substantive domain behavior the schema does not: the 2% accrual discount per year outside the Netherlands and the inclusion of vakantiegeld in the gross figure. It omits nothing critical, though it does not disclose precision caveats of the 'indicatief' net estimate.

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 computation, followed by usage, exclusions, and prerequisites in a logical order. It is a dense single block rather than separated clauses, but every sentence carries information and nothing is padding.

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 exists so return values need no explanation, and annotations cover the read-only profile. The description supplies the calculation scope, exclusions, and required inputs, leaving only the 'required' wording slightly inconsistent with the schema defaults.

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, but the description adds meaning beyond the schema by tying the 2%-per-year rule to the outside-NL accrual input and referencing woonsituatie (samenwonend). Minor mismatch: it calls woonsituatie 'required' while the schema makes samenwonend optional with a default.

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 specific outputs — AOW-leeftijd, AOW-ingangsdatum, gross (incl. vakantiegeld) and indicative net monthly AOW for single/cohabiting — so the agent knows exactly what is computed. It also explicitly distinguishes itself from nmi_ww_uitkering and nmi_wia_uitkering by naming them. This is a precise verb+resource+scope statement.

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?

"Gebruik bij vragen over wanneer en hoeveel AOW" gives the positive trigger, and "Niet gebruiken voor aanvullend pensioen of WW/WIA" with two named alternative tools gives the exclusion. Both when-to-use and when-not-to-use are explicit.

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