Add a specified number of days to any date and get the resulting ISO date string. Useful for date calculations and scheduling.
Add N days to a date and return the resulting ISO date string.
| Name | Required | Description | Default |
|---|---|---|---|
| days | Yes | ||
| date_string | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations, so the description carries the full burden. It does disclose the output form (ISO date string), which is useful. However it omits behavioral edge cases relevant to date arithmetic: whether negative days are allowed, what happens on an unparseable input date, and month/year rollover behavior.
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 zero filler. Every clause (operation, operand, resource, return form) 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?
An output schema exists, so the return value need not be explained. For a simple two-parameter computation the description is mostly adequate, but the missing input-format contract and edge-case behavior leave an agent guessing on the one input that actually matters.
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 0%, so the description must compensate, and it only partially does. It maps 'a date' to date_string and 'N days' to days, but never specifies the expected input format for date_string (ISO 8601? free text?), which is the critical ambiguity for a date-arithmetic tool.
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 (add), a specific operand (N days) and a resource (a date), plus the return type. An agent immediately knows the operation. It does not explicitly differentiate itself from datetime siblings (parse/format/diff), but the arithmetic operation is unambiguous.
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 when-to-use guidance and no alternatives named. It is implied that this is for date arithmetic rather than formatting or diffing, but the description never says when to reach for it versus datetime_diff or datetime_format.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.