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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so safety is covered. The description still adds real value beyond them: the exact coverage layer (federal only, 2026 pinning for lunar festivals), the deterministic walk algorithm, the REST fallback endpoint, and a docs link. No permission, auth, or rate-limit behavior is described.

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 use/don't-use guidance, which is good, but then pads with a redundant "Outputs:" field list even though an output schema exists, a duplicated JSON example, an internal formula line, and garbled example requests ("...around Ordinary federal working day"). Several blocks do not earn their place.

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, fully described, annotated, output-schema-backed tool, this is close to complete: scope, coverage year, algorithm intent, fallback endpoint and docs are all present. Remaining gaps are stylistic bloat and the absence of a named sibling for routing, not missing operational information.

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 coverage is 100% and both properties carry their own descriptions (date range, signed offset, start-date exclusion), so the baseline is 3. The description restates the inputs and supplies a full JSON example, but that example duplicates the schema's own "examples" block and adds no semantic detail the schema lacks.

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+resource: "Adds or subtracts Pakistan authority-scope working days in exact coverage," and the scope clause ("nationwide federal public-holiday layer only... not a universal provincial... calendar") pins down which calendar it applies. It never names the adjacent siblings (check_pk_working_day, count_pk_working_days), so the add/count/check distinction is left to the name alone.

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 an explicit trigger ("Use this when you need a deterministic Pakistan working-day offset") plus a scope-based exclusion listing provincial, private-employer, bank, exchange, school, court and diplomatic calendars. The exclusion is expressed as a coverage limitation rather than as a redirect to a specific alternative tool, and the "Do not use this when this package covers..." phrasing is grammatically muddled, but the intent is recoverable.

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