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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, yet the description adds real behavioral context: it accounts for deemed service, weekends, bank holidays and court office closures, and it enumerates the outputs computed. That goes meaningfully beyond the structured fields.

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?

Three sentences, front-loaded with the purpose and jurisdiction before the output enumeration and the input requirement. The deadline list is dense but earns its place by conveying what the tool returns in the absence of an output schema.

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 multi-input calculator with no output schema, the description adequately conveys what is computed (the enumerated deadlines) and what is required, plus jurisdiction and the holiday/closure handling. Minor gaps remain around any failure modes or edge-case behavior, but nothing essential for invoking it is missing.

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 and the schema already documents every date parameter and the rightToCostsKind enum. The description only reinforces the minimum required inputs ('right to costs, its kind and date'), adding marginal meaning beyond the schema.

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 (works out) and a tightly scoped resource (the CPR Part 47 detailed assessment timetable in England and Wales), then enumerates the concrete deadlines produced (N252, Points of Dispute, N254, Replies, N258, provisional assessment, payment). This domain specificity distinguishes it from the generic calculate_cpr_deadline sibling, though it never names a sibling to avoid.

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?

It implies when to use it (when you have assessment dates and need the timetable) and states a minimum input requirement ('Give at least the right to costs'). But it offers no explicit when-not guidance and no routing against the many sibling calculators, leaving selection to inference.

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