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

Annotations already declare read-only, idempotent, non-destructive behavior. The description adds useful behavioral detail beyond that: the production start cutoff at 14:00 Berlin time on business days, the earliest/latest delivery date output, and the preferred-date hold-back rule.

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?

The description is front-loaded with the core purpose and needed operational detail. It is appropriately sized, though the second sentence about checkout preferred dates is somewhat tangential to invoking this no-argument tool.

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 zero-parameter, read-only estimate tool with no output schema, the description gives sufficient return context (earliest/latest delivery date, cutoff rule, carrier and country scope). It could be slightly clearer on output format, but it is largely complete.

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 takes zero parameters, so there are no parameter semantics to explain; the baseline for zero parameters is 4. The description mentions checkout preferred-date options, but those are not tool parameters and do not require schema documentation here.

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 states a specific resource and outcome: the expected delivery window for an order placed now, with clear scoping to Germany and UPS/DHL. It is immediately distinguishable from siblings like calculate_price or get_shop_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?

It implies usage for delivery estimates in Germany with UPS/DHL and mentions a checkout preferred-date option, but it does not explicitly say when to use this tool instead of alternatives or when not to use it. The context is helpful but not a full routing guide.

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