aws_start_instance

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

Discloses billing resumption as a consequence, but with no annotations, description should also cover idempotency, required permissions, and behavior if instance is already running.

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?

Exactly two sentences, front-loaded with purpose, followed by critical usage note. Every word earns its place.

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?

Lacks output description and behavior for edge cases (e.g., instance already running). With no output schema, some return value context would help.

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 descriptions already cover both parameters (instance_id and region) at 100%; description adds no additional meaning beyond restating them.

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?

Clear verb 'Start', specific resource 'stopped AWS EC2 instance', and distinguishes from sibling lifecycle tools by specifying state.

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?

Explicitly states when to use (start stopped instance), includes important instruction to confirm with user due to billing implications, but lacks explicit when-not-to-use guidance.

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