AWS MCP Server

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

Annotations provide key hints: readOnlyHint=false (mutation), destructiveHint=false (non-destructive), idempotentHint=true (safe to retry), and openWorldHint=true (supports unknown parameters). The description adds minimal behavioral context beyond this, such as specifying 'in the given region', but does not detail side effects, rate limits, or authentication requirements. No contradiction with annotations exists.

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 that directly states the tool's purpose without unnecessary words. It is front-loaded and wastes no space, making it easy to parse quickly.

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 complexity (mutation with nested parameters) and lack of output schema, the description is minimal. Annotations cover safety and idempotency, but the description does not address return values, error conditions, or advanced usage scenarios, leaving gaps for an agent to infer behavior.

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 detailed descriptions for nested parameters like 'AssignIpv6AddressOnCreation' but not for top-level ones like 'region'. The description mentions 'subnet ID' and 'region', aligning with the schema, but does not add significant meaning beyond what the schema provides, such as explaining parameter interactions or 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 description clearly states the action ('Update') and resource ('subnet attributes by subnet ID in the given region'), making the purpose evident. However, it does not differentiate from sibling tools like 'update-vpc-attribute' or 'update-db-instance', which have similar update patterns but target different resources, so it lacks explicit sibling distinction.

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, such as 'create-subnet' for initial setup or 'list-subnets' for viewing. It also lacks prerequisites, like needing specific AWS permissions or network configurations, leaving usage context unclear.

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