get_detailed_breakdown_by_day

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

Despite no annotations, the description discloses the return structure (nested dict and formatted string) and that it takes a days parameter. It reveals the output format fairly well, though it could mention limitations like max days.

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 concise and structured with Args and Returns sections. The main purpose is front-loaded. Minor wordiness in Returns could be tightened.

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?

There is an internal contradiction: the purpose mentions 'instance type' but Returns only mention 'date, region, and service'. Also, Returns states 'Dict[str, Any]' then says it's a tuple. The description lacks structural details of the nested dictionary. Given no output schema and no annotations, completeness is insufficient.

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 description adds minimal value over the schema: it says 'Parameters specifying the number of days to look back,' but the schema already states that for DaysParam. It does not mention the default of 7, optionality, or constraints. With 0% schema coverage, the description should compensate more.

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 daily spend breakdown by region, service, and instance type. This specific verb and resource differentiate it from sibling tools about bedrock usage and EC2 spend.

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 on when to use this tool versus siblings. It does not mention prerequisites, alternatives, or context for selection.

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