AWS MCP Server

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

With no annotations provided, the description adequately discloses return values ('Returns instance details including ID, type, state, IPs, and tags') which substitutes for the missing output schema. However, it omits operational details such as pagination behavior, safety confirmation (read-only nature), or authentication requirements that annotations would typically provide.

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 efficiently structured in three sentences: purpose declaration, input/filtering capabilities, and output specification. There is no redundant information or wasted words; each sentence earns its place by conveying distinct information.

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 lack of output schema, the description appropriately documents the return structure. It covers the essential filter mechanisms for an EC2 describe operation. However, given the complexity of AWS operations and the presence of a potentially dangerous sibling tool (`manage_instances`), it could benefit from explicit safety confirmation or pagination details.

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?

With 100% schema description coverage, the schema already documents all parameters clearly. The description adds marginal semantic value by mapping 'filters' to concrete examples (state, tags), but does not elaborate on parameter interactions, syntax beyond the schema's provided JSON example, or the optional nature of all parameters.

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 (Describe) and resource (EC2 instances), and lists specific filterable attributes (IDs, state, tags). However, it does not explicitly distinguish this read-only tool from its sibling `aws_ec2_manage_instances`, leaving the agent to infer the difference from naming conventions alone.

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 implies usage patterns by listing filter options (instance IDs, state, tags), suggesting when to use specific parameters. However, it lacks explicit guidance on when NOT to use this tool or when to prefer `aws_ec2_manage_instances` instead, and does not clarify the relationship between `instance_ids` and `filters` parameters.

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