AWS MCP Server

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

With no annotations provided, the description carries the burden of behavioral disclosure. It adds valuable context with '(one per region)' indicating the cardinality of results, but lacks information about required permissions, whether the operation is read-only/safe, or pagination behavior for accounts with many regions.

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 with no waste. The parenthetical '(one per region)' earns its place by providing crucial scope information. Front-loaded with the action verb and resource type.

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 simple 2-parameter list operation with no output schema, the description is adequately complete. The '(one per region)' clause provides essential behavioral context for AWS's regional service architecture. However, lacking output schema, it could benefit from hinting at the return structure (list of strings/IDs).

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 both 'profile' and 'region' well-documented in the schema. The description mentions 'in the account' and 'per region' which loosely maps to the parameter concepts, but does not add syntax details, format constraints, or semantic relationships between parameters beyond what the schema already provides. Baseline 3 is appropriate.

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 clearly states the verb (List), resource (GuardDuty detector IDs), and scope (one per region). It implicitly distinguishes from sibling 'get_detector' by indicating it returns IDs rather than full objects, and from 'list_findings' by specifying 'detector IDs'. However, it does not explicitly name sibling alternatives for clarity.

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?

The description provides no guidance on when to use this tool versus alternatives like 'get_detector' or 'list_findings', nor does it mention prerequisites such as configuring AWS credentials or permissions required (GuardDuty might need specific IAM permissions).

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