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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely new behavioral context: the step-by-step formula, the deterministic guarantee, and a direct REST fallback endpoint with a warning not to guess another path.

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?

Purpose is front-loaded, but the description carries redundant filler: a repeated 'Example user requests' line with an awkward fragment ('Bangkok-only event remains conditional') and an 'Outputs' enumeration that duplicates the existing output schema. These sentences do not earn their 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?

The description covers scope, computation, inputs, a full example, formula, REST fallback, and docs link, and an output schema already exists so return values need not be explained. The only gap is that listing output fields is redundant rather than informative, but nothing an agent needs to call it correctly is missing.

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% and the schema already documents both parameters, including the signed-offset semantics. The description restates the inputs and provides a complete JSON example, which is helpful but adds no meaning beyond the schema. Baseline 3 applies.

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?

States a specific verb+resource ('deterministic Thailand working-day offset') and scopes it to an authority calendar (Bank of Thailand financial-institution), which distinguishes it from the many sibling country tools. It does not explicitly name which sibling to prefer, but the scope statement is concrete enough for selection.

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?

Gives explicit when-to-use ('Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery') and an explicit when-not ('Do not use this when this is a Bank of Thailand financial-institution calendar, not a universal Thai employee, government, employer, exchange or payment-settlement calendar'). The exclusions route the agent away from incorrect scope interpretations.

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