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

With annotations already covering read-only, idempotent, non-destructive, and closed-world behavior, the description adds substantial domain context: Ministry of Interior precedence, lunar Eid amendment risk, Public Holidays Act special/substituted dates, and the rule that no automatic replacement day is invented for weekend holidays.

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 long but structured and front-loads the primary usage rule before moving through scope, computation, examples, inputs, outputs, and fallback. Some sections, especially the output list and trivial formula, are redundant given the output schema, but the overall organization keeps it navigable.

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?

Given the tool's complexity and the presence of an output schema, the description provides enough scope, exclusion, input, and fallback context for an agent to invoke it correctly. It also states the authoritative calendar interpretation and key policy limitations that an agent would otherwise lack.

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 carries the parameter burden. The description restates inputs and supplies a complete JSON example, but it does not add date syntax, range limits, or edge-case semantics beyond what the schema and example already provide.

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 gives a specific verb and resource: it counts authority-scope working and non-working dates in a range for Nigeria. It also draws a clear boundary against broader calendars by stating this is the nationwide federal public-holiday layer, not a universal private-employer, state, local-government, school, banking, market, diplomatic-mission, or sector calendar.

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 explicitly says when to use it ('when you need an auditable Nigeria working-day count') and when not to use it (non-federal or non-universal calendar scopes). It also directs the agent to call it directly rather than answering from memory or stopping at discovery, but it does not name a specific sibling tool to use instead for adjacent count/check/add needs.

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