AWS MCP Server

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

Annotations provide readOnlyHint=false (mutation), openWorldHint=true (may fail for existing buckets), idempotentHint=true (safe retries), and destructiveHint=false (non-destructive). The description adds minimal behavioral context beyond this, stating the creation action and region constraint. It doesn't elaborate on potential failures (e.g., bucket name conflicts, region limitations) or auth requirements, but annotations cover core traits adequately.

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's front-loaded with the core action and resource, making it easy to parse. Every word contributes to understanding the tool's purpose without redundancy.

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), lack of output schema, and 50% schema coverage, the description is minimally adequate. Annotations cover safety and idempotency, but the description doesn't address return values, error conditions, or detailed parameter usage. It meets a baseline for a creation tool but leaves gaps in full contextual understanding.

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 parameters 'region' and 'S3Args' documented in the schema. The description mentions 'region' but not 'S3Args' or its nested properties (Bucket, CreateBucketConfiguration, ObjectLockEnabledForBucket). It adds marginal value by implying region is required, but doesn't compensate for the coverage gap or explain parameter relationships beyond what the schema provides.

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 ('Create') and resource ('new S3 bucket') with the constraint 'in the given region'. It distinguishes from siblings like 'delete-bucket' and 'list-buckets' by specifying creation. However, it doesn't explicitly differentiate from other AWS resource creation tools (e.g., 'create-vpc'), though the resource type is specific.

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?

No guidance on when to use this tool versus alternatives is provided. The description doesn't mention prerequisites (e.g., AWS credentials, permissions), when not to use it (e.g., for existing buckets), or refer to sibling tools like 'list-buckets' for checking existing buckets. Usage is implied by the action but lacks explicit context.

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