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

Annotations already indicate the tool is read-only, idempotent, and non-destructive. The description adds useful behavioral context by specifying what the result contains: per-day amount, total in the scheme's currency, partial-day fraction, and scheme-specific meal deductions. It also notes the tool is free and unlimited, which is additional practical context beyond the annotations.

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 concise and front-loaded with the core action and result composition. The 'Free and unlimited' sentence is a useful standalone note. It could be slightly more readable if the first sentence were split, but it contains no wasted content.

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?

There is no output schema, so the description must carry return-value information; it names the main outputs but not the full result shape or how scheme-specific optional parameters like fiscal_year, late_evening, and lodging_nights affect the result. The rich input schema covers parameter semantics well, but for a 10-parameter tool with multiple scheme-specific behaviors, the description alone is not fully 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?

Schema description coverage is 100%, so the structured schema already documents all parameters thoroughly. The description adds little parameter-level meaning beyond mentioning meal deductions and partial-day fractions, which loosely map to meals_provided and start/end. This meets the baseline but does not significantly augment the schema.

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 verb and resource: 'Calculate the daily travel allowance for one trip' and enumerates the key outputs (per-day amount, total in scheme currency, partial-day fraction, meal deductions). This makes it clear that this tool computes a per-trip allowance, distinguishing it from a sibling like perdiem_rates that would provide rate tables rather than a calculated allowance.

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 implies the primary use case—calculating an allowance for one trip—but does not explicitly state when to prefer this tool over perdiem_rates or perdiem_report. It also does not mention required inputs or conditions like needing a scheme, destination, and date range, leaving usage boundaries to inference.

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