AWS MCP Server

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

Annotations provide readOnlyHint=true, destructiveHint=false, openWorldHint=true, and idempotentHint=true, covering safety and idempotency. The description adds the region constraint, which is useful context beyond annotations. However, it doesn't disclose behavioral traits like pagination (implied by NextToken in schema), rate limits, authentication needs, or what 'all' entails (e.g., includes default subnets). No contradiction with annotations.

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 a single, efficient sentence with zero waste—it directly states the tool's purpose and key constraint. It's appropriately sized and front-loaded, making it easy to parse without unnecessary elaboration.

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's moderate complexity (2 parameters with nested objects), rich annotations, and no output schema, the description is minimally adequate. It covers the basic action and region scope but lacks details on usage, parameter nuances, or return values. With annotations handling safety, it's complete enough for a simple list operation but could be more informative.

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 50%, with the 'region' parameter well-documented but 'SubnetArgs' having nested properties described. The description mentions 'region' but adds no semantic details beyond the schema (e.g., format, valid values). It doesn't explain 'SubnetArgs' or its filters, leaving gaps. Baseline is 3 due to moderate schema coverage, but description doesn't fully compensate.

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 action ('List all the subnets') and specifies the resource ('subnets') with a scope constraint ('in the given region'). It uses a specific verb ('List') that distinguishes it from creation/deletion tools, though it doesn't explicitly differentiate from other list tools like 'list-vpcs' or 'list-security-groups' beyond the resource type.

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 no guidance on when to use this tool versus alternatives. It doesn't mention sibling tools like 'list-vpcs' for related resources, nor does it specify prerequisites (e.g., needing AWS credentials) or exclusions (e.g., not for filtering by specific attributes beyond region). The context is implied but not explicit.

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