AWS MCP Server

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

No annotations provided, so the description carries full disclosure burden. While 'describe' implies read-only, the description doesn't explicitly state safety (read-only), pagination behavior, rate limiting, or what occurs when called without filters (returns all subnets in all regions?).

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?

Single sentence with no redundancy or filler. However, given the lack of annotations and output schema, the extreme brevity represents under-specification rather than optimal conciseness—could front-load more critical behavioral context.

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?

With 4 parameters, no annotations, and no output schema, the one-sentence description is insufficient. It doesn't hint at return contents (subnet CIDRs, AZs, states), explain AWS credential requirements, or clarify the relationship between subnets and VPCs in the returned data.

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 coverage is 100%, establishing a baseline of 3. The description mentions 'optionally filtered by VPC' which maps to the vpc_id parameter, but adds no semantic context for profile/region credentials or the subnet_ids array parameter beyond what the schema titles already convey.

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 states the specific action (Describe) and resource (subnets) clearly, and mentions the VPC filter capability. However, 'describe' is somewhat generic AWS terminology and doesn't explicitly differentiate from the sibling aws_vpc_describe_vpcs beyond the resource name itself.

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 provided on when to use vpc_id vs subnet_ids parameters, when to call without filters, or any prerequisites like requiring a valid AWS profile. No alternatives or exclusions mentioned despite multiple filtering options available.

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