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 successfully documents the pagination behavior (1000 object limit, continuation_token usage) but omits explicit safety classification (read-only nature) and error behaviors (e.g., bucket not found scenarios).

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 zero waste: first establishes purpose and filtering, second establishes limits and pagination. Information is front-loaded and appropriately sized for the tool 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?

For a 6-parameter list operation with 100% schema coverage, the description covers core purpose, filtering, pagination mechanics, and result limits. Missing output format details (since no output schema exists), but the count constraint provides sufficient behavioral context for invocation.

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%, so baseline is 3. The description mentions 'prefix filter' and 'continuation_token for pagination' which provides contextual mapping, but does not add syntax details or format constraints beyond the comprehensive schema descriptions.

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 verb 'List' with resource 'objects in an S3 bucket' and clarifies the optional prefix filter. It clearly distinguishes from siblings like aws_s3_list_buckets (buckets vs objects) and aws_s3_get_object (single retrieval vs listing).

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?

Description provides implicit guidance by documenting the 1000-object limit and continuation_token for pagination, indicating when pagination is needed. However, it lacks explicit when-to-use guidance comparing this to get_object for single-object retrieval or alternative filtering approaches.

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