aws_multi_region

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

The description adds behavioral context beyond annotations: it explains that partial failure is expected, describes the return format (array of result objects), and clarifies that duplicate regions are collapsed. Annotations are neutral (no contradictions), and the description appropriately supplements them, though it does not address mutation safety explicitly (but annotations indicate non-destructive).

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 three sentences: core purpose, shape comparison, and behavioral caveats. It is front-loaded with the main action, uses no filler, and every sentence adds critical information. This is highly efficient.

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 the tool has 9 parameters (3 required), no output schema, and 100% schema coverage, the description sufficiently covers the important contextual details: parallel execution, return format, duplicate handling, and partial failure. It aligns with complexity and annotations, leaving no major gaps.

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%, so the input schema already documents each parameter. The description adds value by explaining the tool's similarity to aws_call and mapping the parameter set, emphasizing the regions array difference. It also details the return shape and duplicate behavior, which goes beyond schema descriptions.

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's purpose: running an AWS API operation across multiple regions in parallel. It explicitly distinguishes from its sibling aws_call by noting the key difference: using an array of regions instead of a single region. Examples like 'describe-instances across all our regions' reinforce the action and resource.

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 explicit use cases ('Use for fleet-wide reads') and concrete examples (describe-instances, list-buckets, check IAM password policy). It warns about partial failure and explains duplicate region handling. However, it does not explicitly mention when not to use the tool or list alternatives beyond the implicit comparison to aws_call.

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