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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description doesn't need to restate safety. It adds context by stating the values are consistent with an external URL, which clarifies the data source and reliability. This goes slightly beyond the structured 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 a single, concise sentence that front-loads the core functionality and includes a helpful reference URL. Every word is purposeful, with no redundancy or fluff.

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 read-only lookup tool with a rich output schema and clear annotations, the description is nearly adequate. It identifies the data source and purpose, but it omits any mention of pagination behavior, which is implied by the input parameters. Still, the output schema and annotations cover many details, making the description sufficient for most use cases.

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 input schema has 0% description coverage, and the description does not explain the 'request' object, page_size, or starting_token. The parameter names hint at pagination, but the description adds no semantic value, forcing the agent to guess from examples. Given the low coverage, the description should compensate, but it does not.

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 tool's purpose: 'Check the unit consumption for each API.' It uses a specific verb ('check') and resource ('unit consumption'), and it links to an official pricing page to further clarify what the tool accesses. This clearly distinguishes it from sibling tools, which focus on AI transformations and file operations.

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 when to use the tool (when you need to know unit consumption/costs), but it does not explicitly state usage contexts or exclude alternatives. It provides a reference URL for consistency but lacks guidance on when to prefer this tool over others, though such guidance is not critical since no sibling tool overlaps in purpose.

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