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

With no annotations, the description carries the full burden of behavioral disclosure. It does convey that the tool is observational ('observed change timeline') and implies a read-only operation by saying it 'Returns' data. However, it leaves ordering, time range, and limit semantics unspecified.

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 short sentences with no filler. The rhetorical opener makes the purpose memorable, and the usage example earns its place by illustrating how the tool should inform decisions.

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 two-parameter read tool, this is adequate but has gaps: it never explains what limit controls, what time window is covered, or how 'totals' are computed. With no output schema, those details would materially help an agent call the 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 coverage is 0%, and the description only weakly hints at subjectKey through the phrase 'for a subject.' The limit parameter is never mentioned at all, so the description does not compensate for the missing schema documentation.

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 what the tool does: it returns an observed change timeline and totals for a subject. The purpose is specific enough to be usable, though it does not explicitly differentiate itself from the sibling what_changed_since.

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 clear context for when to use the tool: to set your own re-check cadence based on volatility. It provides a concrete example of the reasoning, but it does not mention when not to use it or compare it with alternatives.

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