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

The description adds one behavioral detail: the adapter drains NextPageToken internally, handling pagination automatically. This is useful beyond the annotations, which already declare read-only and idempotent. However, the mention of 'daily breakdown' could mislead since granularity can be monthly or hourly per the schema, and no other behavioral traits (e.g., rate limits, authentication) are disclosed.

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 very concise, consisting of two sentences. It front-loads the core purpose and adds only one extra detail (pagination). There is no wasted wording, and it is well-structured for quick comprehension.

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?

Despite being a read-only tool with annotations, the description is insufficient for a tool with 6 parameters, no output schema, and zero parameter documentation. It does not explain the expected return format, date handling, or how 'normalized' data is structured. The pagination note is helpful but does not address the overall lack of context needed for effective 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?

The input schema has zero parameter descriptions (0% coverage), and the description does not compensate. It fails to explain the meaning or format of account, start_date, end_date, days_back, group_by, or granularity. The high-level mention of 'daily breakdown' and 'top services' does not map to parameters, leaving the agent without essential information to construct valid requests.

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 it retrieves normalized AWS Cost Explorer cost and usage data with daily breakdown and top services. It identifies the specific resource (Cost Explorer) and the operation (get), making the tool's purpose unambiguous and differentiated from sibling tools like anomaly detection or forecasting.

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 guidance is provided on when to use this tool versus alternatives such as aws_billing_anomalies or aws_billing_forecast. The description does not mention any exclusions, prerequisites, or preferred contexts, leaving the agent to infer usage without explicit direction.

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