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

Annotations already cover safety (readOnly, idempotent, closed-world), so the bar is lower. The description adds meaningful domain behavior beyond annotations: it compares annuïteit vs draagkracht and returns the lower amount, and it specifies the two regelingen. It stops short of covering edge cases or output details, hence not a 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?

Front-loads the calculation purpose, then usage guidance, exclusions, and required inputs in a compact paragraph. Every sentence earns its place with no redundancy.

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?

Given a rich input schema, full annotations, and an output schema that handles return values, the description provides everything needed: what the tool calculates, when to use it, when not to use it, and the minimum required inputs. No critical gaps remain.

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 schema already documents all four parameters in detail. The description only restates the required inputs ('schuldbedrag, regeling en inkomen') without adding syntax, constraints, or meaning beyond the schema. Baseline 3 is appropriate.

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 ('Berekent'), resource ('maandbedrag voor terugbetaling van een DUO-studieschuld'), and calculation logic (wettelijk maandbedrag vs draagkracht; lowest applies). It distinguishes itself from siblings by explicitly naming nmi_bruto_netto and excluding hypotheekruimte.

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?

Explicitly says when to use ('Gebruik bij vragen over aflossing van studieschuld') and when not to use ('Niet gebruiken voor hypotheekruimte ... of netto loon (gebruik nmi_bruto_netto)'). Names the correct alternative tool for an out-of-scope use case.

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