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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds useful behavior: the scenario-count bound and the fact that results are expressed as a difference in net pay from the first scenario. It does not cover error cases (e.g., what happens below 2 scenarios).

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?

One dense sentence that front-loads the verb and scope, then layers in the enumerated scenario types and the output framing with zero filler.

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?

With no output schema, the description does the work of explaining the return shape ('the difference in net pay from the first'), which is the key thing an agent needs. It is nearly complete, missing only guidance on the single-scenario sibling and per-field semantics.

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 0%, and the description compensates partially by naming the scenario dimensions (pension changes, Scotland, student loans) that map to nested fields. However, it says nothing about taxYear, pension method enum, childBenefitAnnual, or the region codes, leaving several properties to be inferred from the schema alone.

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 (Compare) and resource (UK pay scenarios), plus the bounds (2 to 5) and the scenario types covered (pay rises, pension changes, region moves, student loans). It implicitly distinguishes itself from calculate_take_home by being multi-scenario, but never names the sibling outright.

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?

The examples of scenario types give implied context for when to reach for this over a single calculation, but there is no explicit when-to-use rule or when-not guidance naming calculate_take_home as the single-scenario alternative.

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