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

No annotations exist, so the description carries the full load. It does disclose the return shape (rate percentage plus annual and biweekly amounts), which is genuinely useful, but says nothing about the effect of omitting the optional date, what happens with an invalid/non-DSSR postcode, or any auth/rate constraints. Read-only calculation is the obvious behavior, so the risk is low.

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?

Two short sentences, front-loaded with the resource and followed by return values. Minor redundancy between 'COLA calculator' and 'COLA calculations', but nothing wasteful.

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?

For a four-parameter tool with no annotations and no output schema, describing the three return values is a real contribution. However, the semantics of the optional date (default, as-of behavior) and postcode validity handling are left entirely to the caller's assumptions.

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 postcode, family_size, base_salary and date, including format and units. The description adds no parameter-level meaning beyond that, so the baseline 3 applies; notably it never mentions the optional date parameter or its 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?

States a specific verb and resource (COLA calculation for a DSSR postcode) and names the concrete outputs (percentage rate, annual and biweekly amounts), which clearly separates it from the mileage and per-diem calculators in the sibling list. It doesn't explicitly name an alternative, but the resource is distinct enough to route on.

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 line about automating COLA calculations and replacing the official excel file implies the intended usage context, but there is no when-to-use vs when-not guidance and no mention of the other calculation tools (mileage, per diem) or of prerequisites such as having a valid DSSR postcode.

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