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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: the default date behavior, that it reports additions/removals/layer changes, and that results are factual data only with no recommendations. This goes beyond what annotations alone provide.

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 sentences, front-loaded with the core behavior and default, followed by a clear use case and a useful factual-data caveat. Every sentence earns its place with no redundant filler.

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?

Given the tool has only two parameters, full schema coverage, and strong safety annotations, the description is largely complete. It explains the default date, scope of changes, and usage intent. It could clarify the term 'cleared more or fewer layers' slightly, but nothing essential is missing for an agent to invoke it 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 coverage is 100%, so the schema documents both parameters well. The description adds extra meaning by explaining the default for `since` (previous daily snapshot) and clarifying `stack` as a slug from list_stacks, which helps the agent understand how to populate both fields correctly.

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 identifies the resource (a stack), the action (reporting what entered, left, or changed layers since a date), and the intended use case. It is distinguishable from siblings like list_stacks and run_stack by focusing on changes over time, though it does not explicitly name alternatives.

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 concrete usage context: 'what is new in this list today / this week', and clarifies the default comparison point (previous daily snapshot). It does not explicitly state when not to use it or mention sibling tools as alternatives, but the context is clear enough.

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