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 but fails to mention key traits: that this is a read-only operation, pagination behavior with max_items, required IAM permissions (iam:ListUsers), or what the return structure looks like. Only the filter constraint is mentioned.

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?

The description is a single, efficient sentence (11 words) that front-loads the primary action. Every word earns its place by conveying the core operation and the key filtering capability without redundancy.

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 100% schema coverage and 4 parameters with no output schema or annotations, the description provides the minimum viable context for a list operation. It adequately complements the detailed schema but lacks richness regarding AWS-specific behaviors, permissions, or result pagination that would be expected for cloud infrastructure tools.

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 description coverage is 100%, establishing a baseline of 3. The description adds 'optional' context for path_prefix, though this is redundant with the schema's default value ('/'). It does not add semantic context for profile, region, or max_items beyond the schema definitions.

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 action (List) and resource (IAM users) with a specific scope (optional path prefix filter). It distinguishes from siblings like aws_cognito_list_users by specifying 'IAM users' and from aws_iam_list_roles/policies by naming the specific resource type, though it doesn't explicitly contrast with alternatives.

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 mentions the path prefix filter is 'optional', hinting at usage flexibility, but provides no explicit guidance on when to use this tool versus alternatives like aws_cognito_list_users, or when filtering by path prefix is appropriate versus other filtering strategies.

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