Add or subtract days, weeks, months, years, or business days from any date, correctly handling leap years and month boundaries for accurate results.
Add or subtract days/weeks/months/years/businessDays from a date, handling leap years and month boundaries correctly
| Name | Required | Description | Default |
|---|---|---|---|
| date | Yes | ISO 8601 date/datetime, e.g. "2026-03-03" | |
| unit | Yes | ||
| amount | Yes | Positive or negative integer amount |
Changes observed during successful MCP inspections.
v2.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It does add meaningful detail by promising correct handling of leap years and month boundaries, which is useful for date arithmetic. However, it does not disclose the return format, behavior on invalid dates, or the exact semantics of businessDays (e.g., weekday-only vs. holiday-aware).
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 communicates the operation, supported units, and a key correctness guarantee with no filler. Every phrase earns its 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?
The description is adequate for a straightforward date arithmetic tool, and the required parameters are clear from the schema. However, there is no output schema and no mention of what the tool returns, so an agent must infer the return type and format. Some edge-case semantics, especially for businessDays, are left unexplained.
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?
The schema already describes date and amount, and the enum lists the possible units. The description reinforces how the parameters combine (add/subtract amount of unit to/from date) and mentions businessDays, but it does not clarify the nuances of that unit. Coverage is moderate, so the description provides only marginal additional 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?
The description names a precise operation — add or subtract — and a clear resource (a date), and it enumerates the exact supported units including businessDays. This makes it readily distinguishable from sibling tools like date_diff, convert_timestamp, and parse_date.
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?
No guidance is given about when to choose this tool over alternatives such as date_diff or convert_timezone. The context of sibling tools suggests a potential for confusion, but the description provides no exclusions or alternative routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.