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 explains the calculation factors, the settlement_type values and their implications, and even provides instruction on handling relative dates via the `today` block from other tools, which helps agents use it correctly.

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 long but well-structured, with a lead sentence, a bulleted list of behavioral factors, an Args list, and examples. Every sentence adds value, and the format makes it easy to scan.

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?

This tool has six parameters with conditional requirements, and the description covers all of them, provides example calls, and addresses the nuance of the default from_date. The output schema exists, so not describing return values is acceptable. The description is complete for agent use.

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%, so the description's detailed Args section is essential. It provides country/currency formats, default values, conditional requirements (e.g., FX currencies required for fx_spot), and settlement_type semantics, fully compensating for the sparse 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 opens with a specific verb ('Calculate') and resource ('value/settlement date for a payment'), and elaborates on the inputs that affect the result. This clearly differentiates it from sibling tools like settlement_eta or fx_timing_advisor, which target different aspects of payment timing.

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 strong sense of when to use the tool—for determining settlement dates with holiday/weekend/convention logic—and includes worked examples for common scenarios. However, it does not explicitly name alternative tools or list exclusions (e.g., 'use settlement_eta for expected arrival times'), so it earns a 4 rather than a 5.

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