AWS MCP Server

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

With no annotations provided, the description carries the full burden. It discloses the DryRun=True behavior for readonly mode, which is crucial safety information. However, it omits other behavioral details like async execution nature, idempotency guarantees, or what the response contains.

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?

Two sentences with no waste: the first states the core purpose immediately, and the second provides essential safety context about dry-run behavior. Appropriately sized for the tool's complexity.

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?

As a mutation tool with no output schema, the description adequately covers the safety mechanism (DryRun) but should ideally explain what successful execution returns or failure modes look like. Sufficient but with gaps regarding the operation results.

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 100%, establishing a baseline of 3. The description mentions the action values (start, stop, reboot) which aligns with the schema enum but doesn't add syntax, format examples, or inter-parameter constraints beyond what the schema already 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 uses specific verbs (start, stop, reboot) and identifies the exact resource (EC2 instances). It clearly distinguishes this from sibling describe tools like aws_ec2_describe_instances by emphasizing state-changing actions.

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 explains the dry-run behavior for permission validation, which provides some usage context. However, it lacks explicit guidance on when to use this tool versus read-only alternatives or prerequisites like instance ID discovery.

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