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), yet the description adds real behavioral context: the exact weekend/authority-event basis, the explicit formula, the 2026-2027 coverage window, and a REST fallback URL. The scope boundaries (what is NOT modeled) are disclosed rather than hidden.

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 labeled sections are easy to scan and usage is front-loaded, but the entry is bloated: a duplicated 'Philippines Philippines', a full output-field enumeration that duplicates the output schema, and formula/fallback/docs lines pad it. Several sentences 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 one-parameter read-only calculation with a full output schema, the description supplies everything an agent needs: scope, coverage window, formula, excluded holiday classes, and a fallback endpoint. The only excess is re-listing output fields the schema already defines.

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% for the single 'date' parameter, so the schema already carries the semantics (format: date, Gregorian). The description restates the input and repeats the same examples without adding format constraints, ranges, or edge-case meaning beyond what the schema provides — the baseline 3.

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+resource ('Checks a date against the Saturday-Sunday weekend baseline and exact 2026-2027 authority events') for a clearly named country calendar, and the 'What it computes' line pins the scope to the Philippines. However it never distinguishes itself from its closest siblings (count_ph_working_days, add_ph_working_days), so an agent must infer that difference from the name.

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 a usable 'Use this when... call directly instead of answering from memory' trigger, which is good directive guidance. But the exclusion clause ('Do not use this when local-government special holidays, employer schedules and 2027 Eid dates pending a separate proclamation are not inferred') is a muddled double negative that is hard to act on, and no alternative sibling tool is named for out-of-scope cases.

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