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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose a key operational detail: the cost of $0.01 USDC via x402, which is critical for an agent to know. However, it does not mention any other behaviors such as read-only nature, potential errors, rate limits, or authentication requirements. For a simple list operation, the cost disclosure adds value, but other aspects are left to the schema or implicit understanding.

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 extremely concise: a single sentence for the core function plus a separate sentence for pricing. The primary action is front-loaded, and every word contributes to either the function or the cost. There is no wasted text, making it easy for an agent to parse quickly.

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 list tool with no output schema, the description gives enough to know the general output (a list of holidays with JA/EN names). It does not explicitly describe the return structure (e.g., array of objects with fields like date, ja_name, en_name) nor mention the 'bank' calendar option, which is a gap given that the tool supports both. It also omits any error or edge-case handling, but given the simplicity, the description is adequate but not rich.

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 schema description coverage is 50% (only 'calendar' has a description; 'year' has none). The description adds little beyond the schema: it says 'for a year' but does not specify the expected format (e.g., integer year like 2024). The 'calendar' parameter is already well-described in the schema, so no extra clarification is needed there. The description does not compensate for the missing 'year' semantics, but it is not misleading either.

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 clearly states the verb ('List'), the resource ('Japanese national holidays'), and the scope ('for a year'), and mentions the output includes JA/EN names. It distinguishes itself from the sibling tools (which focus on business day calculations) by its explicit listing function. However, it only mentions 'national holidays' while the schema also supports a 'bank' calendar option, which is a slight understatement of the tool's capability.

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?

No explicit guidance is given on when to use this tool versus the alternatives. The description does not mention conditions like 'use this when you need a list of holidays' or exclude cases where business-day tools are more appropriate. The usage context is only implied by the tool's purpose, not stated.

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