AWS MCP Server

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

No annotations provided, so description carries full burden. References STS GetCallerIdentity API (read-only by nature) and mentions it returns account/role info, but omits permission requirements, output format structure, or rate limits.

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 well-structured sentences: first defines the operation, second explains value proposition. Zero redundancy, appropriately front-loaded with the core action.

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?

Complete for a simple 2-parameter diagnostic tool. No output schema exists, but description implies identity return values by mentioning 'account and role.' Mention of STS API name helps experienced users infer expected response structure.

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% with complete descriptions for 'profile' and 'region'. Description mentions 'for a profile' linking to the profile parameter but adds no syntax details or validation rules beyond the schema.

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 specific verb 'Get' + resource 'IAM identity' with explicit AWS API reference 'STS GetCallerIdentity'. Uniquely distinguishes from 150+ sibling tools which operate on specific AWS services (EC2, S3, etc.) rather than identity verification.

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?

States 'Useful for verifying which AWS account and role are active for a profile,' providing clear diagnostic context. Lacks explicit 'when not to use' guidance, but this is a unique STS operation with no direct alternative on the server.

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