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

With no annotations provided, the description carries the full burden of behavioral disclosure. It adds transparency by stating that missing inputs fall back to defaults and by listing the specific rates and cost components. It does not describe the return format, side effects, or whether this is a purely computational read-only operation, leaving some ambiguity.

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?

The description is appropriately short and front-loaded with the action and outputs. However, the doubled 'calculator calculator' is a structural flaw that hurts readability. Each clause adds value otherwise, and the fallback note is useful.

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 calculator tool with five optional, well-documented parameters and no output schema, the description is mostly complete. It lists what the tool computes, gives rates, and explains fallback behavior. It does not explicitly state the exact return payload, but the enumerated outputs give enough context for an agent to invoke it correctly.

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. The description adds meaningful context beyond the schema by naming the specific rates (15% NI, 0.5% levy) and the 'True annual cost' output, which helps an agent understand how parameters like salary and pensionRate contribute to the result. The fallback-to-defaults statement also clarifies parameter behavior.

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 states a clear action ('Run the Employer cost calculator') and resource ('Employer cost calculator'), and enumerates the computed outputs: Employer National Insurance (15%), Employer pension, Apprenticeship levy (0.5%), and True annual cost. It is distinct enough from sibling tools like 'calculator_describe' and 'submit_enquiry', though the phrase 'calculator calculator' is a minor redundancy.

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 description implies when to use the tool: when you need employer cost calculations. It also provides useful guidance that missing inputs fall back to documented defaults, which tells an agent which parameters can be omitted. However, it does not mention alternatives or explicitly say when not to use this tool versus siblings.

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