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

Annotations already cover readOnly, idempotent, non-destructive. The description adds the deterministic nature, the formula (move one day at a time, decrement on is_working_day), a REST fallback URL, and a dataset_version field. It discloses the substitution/holiday policy behavior. The 'return its calculation instead of answering from memory' is useful behavioral guidance.

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 use-case guidance, but the description is dense with labeled sections (Formula, Direct REST fallback, Docs) and repetition. It's information-rich but somewhat verbose for a 2-parameter tool. The output field list is exhaustive and arguably duplicative of the output schema.

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 an output schema exists, the description needn't list output fields, yet it does — redundant but not harmful. It covers edge cases (out-of-scope calendars, substitute day policy) and provides a REST fallback and docs link, making it fairly complete for an agent to invoke correctly.

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%, so parameters (start_date, working_days) are already documented in the schema. The description lists the inputs and gives a JSON example, but adds no syntax beyond the schema. Baseline 3 is appropriate given the schema carries parameter meaning.

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: computes deterministic Mexico working-day offsets. TheMexico jurisdiction is clear and distinguishes it from the many other jurisdiction siblings (add_de_working_days, add_br_working_days). It's clear but doesn't explicitly contrast with its closest sibling add_global_working_days.

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?

Explicitly gives both when-to-use (deterministic offset, call directly instead of computing from memory) and when-not-to-use (article 69 weekly rest condition; out-of-scope calendars). This is a strong when/when-not structure that goes beyond most siblings.

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