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

With no annotations, the description carries the full behavioral burden, and it does disclose useful traits: incidental holiday skipping, a statutory section citation, and the exclusive start-date convention. It omits error behavior for invalid rules, handling of the jurisdiction default and region, and whether results are deterministic.

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 short sentences, front-loaded with the action and scoping, and each sentence adds distinct information (scope, return values, counting convention). No padding.

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?

An output schema exists so return values did not need restating, yet the description is thin for a 5-parameter tool with zero schema documentation. The opaque required 'rule' parameter and the region/jurisdiction inputs are unexplained, leaving real gaps for correct invocation.

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% across 5 parameters, so the description must compensate. It partially does: 'add (or subtract)' implies negative days values and 'the start date is not counted' defines exclusive counting for start_date, but it says nothing about rule, region, or jurisdiction values.

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 (add/subtract) plus resource (working days) and scopes it to a NZ statute's definition, which cleanly separates it from count_working_days and nz_holidays. It stops short of naming a sibling explicitly, so it is clear but not fully differentiated.

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?

There is no guidance on when to use this versus count_working_days or list_rules, and no prerequisites (e.g. that a valid rule from list_rules is required). Usage is only implied by the verb semantics.

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