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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, and the description adds substantial behavior beyond them: the algorithm ('move one day at a time; decrement remaining only when status.is_working_day=true'), the pinned dataset/version notion, the date-range constraint, and a REST fallback path.

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?

Front-loads the usage decision and keeps each section to one line. It is content-dense rather than padded, though the enumerated output-field list is somewhat redundant given the output schema and slightly lengthens the definition.

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 two-parameter calculation tool it covers everything an agent needs: scope, exclusions, a concrete call example, the computation formula, and a REST fallback with an explicit warning not to guess other paths. Nothing material 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 two parameters are already fully documented with type, range, and the 'start date excluded for non-zero offsets' semantics. The description lists the same inputs but adds no new meaning, so baseline 3 is appropriate.

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 ('Adds or subtracts dates using the pinned OPM federal schedule and US weekend baseline') with an explicit scope (2026-2027 US federal employee/office). It clearly carves itself out from the many sibling date-offset tools by naming the calendar semantics it does not cover.

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?

Gives explicit when-to-use ('need a deterministic US federal employee/office date offset'), when-not-to-use ('state/local/private-employer, exchange or alternate-work-schedule semantics'), and even instructs to call the tool directly rather than answer from memory. The routing guidance is unusually complete.

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