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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), and the description adds real value on top: coverage boundaries, the requirement for refreshed evidence for future calendars, the exact set of output fields, and a REST fallback endpoint. The awkwardly phrased 'Do not use this when this package covers...' sentence is confusing but conveys a real coverage limit.

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-loaded with the when-to-use clause, but the body is bloated: it repeats the schema example, includes a trivial formula line, and spends length on a REST fallback URL and docs link. Most sentences earn their place, but the definition is longer than the tool's complexity warrants.

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 jurisdiction-scoped date-counting tool it is essentially complete: input shape, output field list, coverage limits, and fallback path are all present, and an output schema exists so return-value explanation is unnecessary. Minor confusion from the coverage sentence keeps it from a 5.

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 documents all four parameters with types and defaults. The description restates the inputs and gives a complete JSON example, but adds no semantics beyond what the schema provides, so the baseline of 3 applies.

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 ('Counts authority-scope working and non-working dates in a range') and names the jurisdiction (Colombia) with example requests. However, it never distinguishes itself from the clearly related siblings check_co_working_day (single-date check) and add_co_working_days, leaving the agent to infer the split.

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 when-to-use ('when you need an auditable Colombia working-day count') and an instruction to call it directly rather than answering from memory, plus scope exclusions (municipal, departmental, school, bank, employer, sector schedules not inferred). It does not name an alternative sibling tool, so the routing guidance is incomplete.

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