AWS MCP Server

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

No annotations provided, so description must carry full behavioral disclosure burden. Fails to indicate this is read-only (Safe), whether results are cached, rate limits, or what the returned data structure looks like (counts by severity levels? JSON format?). Only describes the input transformation.

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?

Single sentence, front-loaded with action and scope. No wasted words, appropriate length for the tool's 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?

With 100% schema coverage and 4 simple parameters, basic coverage is achieved. However, lacking annotations and output schema, the description should have explained the return value structure (e.g., 'returns severity counts') and read-only nature to be complete.

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 has 100% description coverage, establishing baseline of 3. Description adds context that the statistics are 'grouped' (helpful for understanding finding_statistic_types), but incorrectly suggests 'finding type' is supported when the enum only contains COUNT_BY_SEVERITY.

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-resource combination: 'Get a count of GuardDuty findings'. Specifies the grouping dimension ('by severity') but inaccurately mentions 'finding type' when the schema enum only supports COUNT_BY_SEVERITY. Fails to explicitly distinguish from sibling tools like list_findings or get_findings.

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?

No guidance provided on when to use this statistics aggregation versus retrieving individual findings (get_findings) or listing them (list_findings). No prerequisites or permissions mentioned despite requiring a detector_id.

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