AWS MCP Server

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

Annotations already provide excellent behavioral context (readOnlyHint: true, openWorldHint: true, idempotentHint: true, destructiveHint: false), so the bar is lower. The description adds value by specifying the regional scope constraint, which isn't covered by annotations. It doesn't contradict annotations and provides useful operational context beyond the structured data.

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 that front-loads the essential information. There's zero wasted language - every word contributes to understanding the tool's purpose and scope. It's appropriately sized for a list operation with good annotations.

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 annotations provide excellent safety/behavioral context and the description adds regional scope, this is adequate for a read-only list operation. However, with no output schema and complex nested parameters (RouteTableArgs with filtering, pagination, permission checks), the description should ideally mention something about filtering capabilities or return format to be truly 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 description coverage is 50%, with the 'region' parameter well-documented but the complex 'RouteTableArgs' object only partially described. The description mentions 'given region' which aligns with the 'region' parameter, but adds no meaningful context about the filtering, pagination, or permission-checking capabilities documented in the schema. The description doesn't compensate for the schema coverage gap.

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 ('route tables') with geographic scope ('in the given region'), making the purpose immediately understandable. However, it doesn't differentiate this tool from other list tools on the server (like list-amis, list-buckets, etc.) beyond the resource type, missing explicit sibling differentiation.

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. It doesn't mention sibling tools like list-subnets or list-vpcs that might be used in related networking contexts, nor does it specify prerequisites or appropriate scenarios for listing route tables specifically.

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