How long ago (or from now) a given ISO-8601 timestamp is, in human form ('3h 42m ago'). Use to check whether an event was really 'yesterday'. Include the UTC offset in the timestamp.
| Name | Required | Description | Default |
|---|---|---|---|
| timestamp | Yes | ISO-8601, e.g. 2026-07-11T09:30:00+02:00 |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the disclosure burden. It reveals the output format (human form) and that it handles past and future timestamps ('or from now'). It does not detail edge cases like invalid timestamps or time zones beyond the UTC offset requirement, but is sufficiently transparent for a simple tool.
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 concise sentences front-load the core purpose and immediate guidance. Every part adds value: purpose, output format, use case, and a practical tip. No wasted words.
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 tool with one required parameter, no output schema, and no annotations, the description fully covers input requirements, output format, and a relevant use case. It is complete enough for an agent to select and invoke this tool 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 description covers 100% of the parameter with an example. The description adds extra guidance: 'Include the UTC offset in the timestamp,' which is not in the schema description and helps ensure correct usage.
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 clearly states the tool converts an ISO-8601 timestamp to a human-readable relative time string ('3h 42m ago'). It provides a concrete use case (checking if an event was 'yesterday') and distinguishes from the sibling tool 'now' by its specific function.
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?
The description gives a clear usage example and an explicit instruction to include the UTC offset. It implies when to use it (converting timestamps to relative time) but does not explicitly state when not to use it or mention alternatives beyond the sibling.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
The two tools have clearly distinct purposes: 'now' returns the current date and time, while 'since' calculates relative time from a given timestamp. There is no overlap or ambiguity.
Both tool names are single words in lowercase, following a simple, consistent naming style. No mixed conventions or irregularities.
With only 2 tools, the server is tightly scoped to basic date/time utilities. This is appropriate for its purpose, as additional tools would be unnecessary for the core functionality.
The tool set covers the essential operations for a time utility: getting current time and computing relative time. A minor gap might be lack of timezone conversion or formatting, but it is largely complete for common use cases.