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

With no annotations provided, the description carries the behavioral burden. It discloses the cache-backed nature, tenant scoping, and the returned min/max stat_date. It stops short of describing empty-cache behavior or date formatting, but for a zero-parameter read accessor this is reasonably transparent.

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 first sentence states the output, and the second sentence gives the practical usage. Every word 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?

For a simple, zero-argument, low-complexity tool with no output schema, the description is complete. It names the return value, the scope, the data source, and the motivating use case, so an agent has enough context 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?

The tool has zero parameters, so there is nothing to document. Per baseline, a parameterless tool receives a 4, and the description appropriately focuses on the returned values rather than inputs.

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 uses a specific verb ('Returns') with a precise resource ('min/max stat_date present in cache') and a scope ('for the authenticated tenant'). It clearly communicates what the tool does and differentiates it from the sibling insights_query_* tools by framing it as a boundary discoverer for query_overview.

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 explicitly states the intended use: 'Use to bound query_overview windows.' This gives clear context for when to call it, though it does not mention exclusion cases or alternative tools beyond the implicit query_overview relationship.

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