AWS MCP Server

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

Annotations already indicate this is a non-destructive, idempotent write operation (readOnlyHint=false, destructiveHint=false, idempotentHint=true). The description adds minimal behavioral context beyond this - it doesn't explain what 'stop' means operationally (e.g., instance state transition, billing implications, or that it's reversible with 'start-ec2-instance'). However, it doesn't contradict the annotations.

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 - a single sentence that states the core functionality. There's no wasted language or unnecessary elaboration, 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?

For a tool that performs a state-changing operation on cloud infrastructure with multiple parameters and no output schema, the description is insufficient. It doesn't explain what 'stop' means in AWS context, doesn't mention the reversible nature (contrasted with 'terminate'), doesn't discuss permissions or error conditions, and provides minimal parameter guidance.

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?

With 50% schema description coverage, the description doesn't add meaningful parameter semantics beyond what's in the schema. It mentions 'region' but the schema already documents this parameter. The description doesn't explain the Ec2Args object or its sub-parameters (InstanceIds, Force, Hibernate, DryRun), leaving significant gaps in parameter understanding.

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 ('stop') and resource ('EC2 instance'), and specifies the region context. It distinguishes from sibling tools like 'terminate-ec2-instance' by focusing on stopping rather than permanent termination, though it doesn't explicitly mention this 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 like 'reboot-ec2-instance' or 'terminate-ec2-instance'. It mentions the region parameter but offers no context about prerequisites, permissions, or appropriate use cases for stopping versus other instance state changes.

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