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 of behavioral disclosure. It effectively explains the critical return format distinction (text files as strings, binary as base64) and partial download capability, though it omits error handling or permission requirements.

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?

Three sentences with zero waste. Front-loaded with core purpose ('Download and return...'), followed by return format specifics and practical usage guidance. Every sentence 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?

Given the lack of output schema, the description appropriately compensates by detailing return value formats (string vs base64). With well-documented schema parameters (100% coverage), this provides sufficient completeness for an S3 get operation, though error scenarios could be mentioned.

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?

While the schema has 100% coverage, the description adds valuable semantic context beyond the schema by explaining the purpose of the 'range' parameter (partial downloads of large files) and how the tool handles different content types.

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?

Description clearly states the specific action ('Download and return the content') and resource ('S3 object'), using precise verbs that distinguish it from sibling list/delete/put operations.

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?

Provides internal usage guidance for the 'range' parameter ('Use 'range' for partial downloads of large files'), but lacks explicit guidance on when to select this tool vs siblings like aws_s3_list_objects or comparative alternatives.

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