AWS FinOps MCP Server

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

With no annotations provided, the description carries full burden and does well by specifying it returns a 'Dictionary with cost breakdown by region and service', clarifying the output structure. It also documents default values for date parameters. However, it doesn't mention potential rate limits, authentication requirements beyond optional parameters, or error conditions.

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 well-structured with a clear purpose statement followed by organized parameter documentation. Every sentence serves a purpose, though the parameter explanations could be slightly more concise. The front-loaded purpose statement immediately communicates the tool's function.

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?

Given 7 parameters with no schema descriptions and an output schema present, the description provides excellent parameter documentation and clarifies the return value format. It covers authentication options and date defaults well. Minor gaps include lack of error handling information and no mention of data freshness or source limitations.

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?

With 0% schema description coverage and 7 parameters, the description fully compensates by providing clear semantics for all parameters: it explains each parameter's purpose, format requirements (e.g., 'YYYY-MM-DD format'), default values, and optional status. This adds substantial value beyond the bare schema.

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 specific action ('Get cost breakdown'), resource ('AWS region and service'), and scope ('for the specified period'). It distinguishes itself from sibling tools like 'get_cost_by_region' and 'get_cost_by_service' by explicitly combining both dimensions in a single breakdown.

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 usage for cost analysis by region and service but provides no explicit guidance on when to use this tool versus alternatives like 'get_cost_by_region' or 'get_cost_by_service'. It mentions the period parameter but doesn't clarify trade-offs or prerequisites for AWS credential options.

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