list_aws_reserved_instances

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

Annotations already mark the operation as read-only and non-destructive. The description goes beyond that by explaining the pagination contract in detail: pass the returned pageToken back as a parameter and stop when no pageToken is present. It also clarifies the default behavior when filters are omitted.

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 substantive sentences are tight and useful, but the first sentence about evaluating commitments and planning purchases is marketing fluff that does not describe this endpoint's behavior and could even mislead an agent. With that sentence removed, the description would be nearly ideal.

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?

For a read-only, paginated list endpoint with no output schema, the description covers the purpose, filter options, default behavior, and pagination stop condition. It does not cover alternative selection or a few parameter details, but an agent has enough information to invoke the tool correctly.

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 description coverage is only 10%, so the description carries real weight here. It names the filterable parameters (state, instance type, instance family, region, offering class) and explains pageToken semantics. It does not explain X-Tenant-Id or maxResults, but those are either self-describing or peripheral given the schema constraints.

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 core statement 'Returns a paginated list of Reserved Instances (RIs) for the specified AWS organization' clearly identifies the verb, resource, and scope. However, the opening marketing sentence about evaluating commitments and automating purchases is broader and not specific to this tool, and no explicit differentiation from sibling tools like list_aws_savings_plans is provided.

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 gives actionable context: use this endpoint to list RIs for an AWS organization, optionally filtering by several dimensions, and omit filters to get all RIs. It does not explicitly mention when not to use it or name alternatives such as list_aws_savings_plans or list_aws_recommendations.

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