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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds nothing beyond the annotations: it does not say what format the result takes, whether holidays are considered, or that the calendar parameter changes the outcome.

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?

A single, front-loaded sentence with no filler. The bilingual duplication is functional for this toolset rather than padding, though it does add length without adding information.

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 simple computation tool with a fully documented schema, the description is minimally adequate. With no output schema, it should have stated the return format (e.g. YYYY-MM-DD) and that the result reflects the selected calendar, but it omits both.

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 the schema itself explains the standard/bank calendar distinction and the extra_holidays/extra_business_days semantics in detail. The description contributes no additional parameter meaning, 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 ('Return') and a precisely scoped resource ('the last business day of the given month'), which is unmistakably distinct from sibling tools like count_business_days or adjust_to_business_day. It does not, however, explicitly route the agent away from any sibling, so it stops short of the top band.

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 no guidance on when to prefer this over adjust_to_business_day, check_business_day, or count_business_days, nor any stated prerequisites such as whether the date is already known. Usage must be inferred entirely from the name.

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