AWS MCP Server

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

With no annotations provided, the description bears full responsibility for disclosing behavioral traits. It fails to indicate this is a read-only operation (though implied by AWS 'Describe' convention), omits pagination behavior, rate limits, costs, or what specific route table attributes are returned. This is a significant gap for an AWS API tool.

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 extremely concise with zero wasted words, front-loaded with verb and resource. However, given the complexity of AWS networking and the lack of output schema, this brevity results in underspecification rather than elegant minimalism.

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?

Without an output schema or annotations, and given this is an AWS EC2/VPC operation with complex return values (routes, associations, propagation), the description is insufficient. It omits the service context (EC2), read-only nature, and relationships between route tables, subnets, and gateways that would guide proper tool selection.

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?

Input schema has 100% description coverage, establishing a baseline of 3. The description adds minimal semantic value beyond the schema, only reinforcing that vpc_id acts as an optional filter. It does not add syntax details, examples, or clarify the relationship between profile/region parameters and the AWS API call.

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 identifies the action ('Describe') and resource ('route tables'), and mentions the optional VPC filter which implicitly distinguishes it from sibling tools like aws_vpc_describe_vpcs. However, it could explicitly clarify that this returns routing configuration data rather than VPC metadata.

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 phrase 'optionally filtered by VPC' provides basic usage context for the vpc_id parameter, but there is no explicit guidance on when to use this tool versus other VPC networking tools (like aws_vpc_describe_subnets or aws_vpc_describe_nat_gateways), no mention of IAM permissions required, or prerequisite setup.

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