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

No annotations are provided, so the description carries the full behavioral burden. It does disclose that output is expressed in two currencies (USD and TWD) and that the required inputs vary by model modality, which is useful context. It says nothing about permissions, rate limits, or what happens with missing modality parameters (e.g. cached_tokens), leaving reasonable gaps.

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?

Two sentences, zero waste. The purpose and currency scope are front-loaded, and the parameter-by-modality rule follows immediately. Every sentence earns its 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?

For a 7-parameter estimation tool with no output schema and no annotations, the description covers the essential decision (which parameters to supply per model type) and states the return currency. Minor gaps remain around cached_tokens and the exact shape of the returned estimate, but nothing critical to correct invocation 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 0% across 7 parameters, so the description must compensate and it largely does: it maps each modality to its correct parameter set, clarifying which of the seven fields to populate for a given model. Only cached_tokens goes unexplained, hence not a full 5.

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 (估算/estimate) and resource (某個 AI 模型 API 的花費), and adds that the result is in both USD and TWD. An agent can tell this is a cost calculator, but it never explicitly contrasts itself with the sibling get_ai_api_pricing, so one point is held back for absent sibling differentiation.

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?

It gives invocation guidance by modality (text→input/output_tokens, image→images, video→seconds, voice→characters), which is genuinely helpful. However it offers no when-to-use versus when-not guidance and does not route the agent to or away from get_ai_api_pricing, so this stays at the implied-usage level.

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