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

Annotations already declare readOnly, idempotent, and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond that: the start date is not counted, and weekends/holidays are skipped (with the bank-calendar nuance living in the schema). It does not describe output format, but for a pure computation the added rules are substantive.

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?

Two sentences, front-loaded with the operation before the worked example. It is slightly inflated by full bilingual duplication, but no sentence is wasted and the counting rule is the right thing to lead with.

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?

There is no output schema, but the description states what is returned (the resulting date) and the counting convention, while the schema fully covers the holiday/calendar inputs. Complete enough to call correctly, with only minor gaps around edge cases like out-of-range N.

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% and every parameter (including calendar, extra_holidays, extra_business_days) is documented bilingually in the schema. The description only restates the negative-days convention, adding no syntax or format detail beyond the schema, so the baseline 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 (return the date) plus the operation (N business days after/before), and the Friday-to-Monday example makes the shift semantics unambiguous versus siblings like count_business_days or check_business_day. An agent can distinguish this offset-return tool from the counting/checking siblings without opening any schema.

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?

Usage is implied by the semantics (compute a date offset by N business days), and the negative-N rule is stated, but there is no explicit when-to-use versus adjust_to_business_day or check_business_day, nor any exclusions or prerequisites. Adequate but leaves routing to inference.

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