get_cost_summary

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

With no annotations provided, the description carries the burden of behavioral disclosure. It indicates a read operation ('Fetches') and output dimensions (service, region, time period), but omits potential details like return format, pagination, or permission requirements. This is acceptable for a simple fetch but leaves some 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, front-loaded with the action and resource, and every word serves a purpose. Second sentence adds concrete use cases without unnecessary detail.

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?

The tool has no output schema and no annotations, so the description must compensate. It covers the core purpose and use cases but does not mention the return structure or clarify date parameter logic (e.g., how period interacts with start/end date). Adequate but not complete.

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 coverage is 100% with all parameters described, so the description adds limited value beyond the schema. It reinforces the grouping behavior ('by service and region') but does not explain interactions between period and custom dates, which the schema also leaves implicit. Baseline 3 is appropriate.

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 fetches AWS cloud cost breakdown by service and region for a given time period. It includes specific use cases ('overall spend, top spending services, or cost by region') and distinguishes this from sibling tools by explicitly naming AWS.

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 provides clear when-to-use guidance ('Use this to answer questions about overall spend, top spending services, or cost by region'). While it does not explicitly mention alternatives or exclusions, the AWS qualifier implies a distinction from Azure/GCP siblings.

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