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. While 'Describe' implies read-only access, the description fails to specify what data is returned (configuration, status, endpoints), whether pagination applies, or required IAM permissions for AWS DocumentDB.

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 extremely brief at only 3 words, avoiding verbosity. However, this brevity borders on under-specification. The single sentence is front-loaded with the action verb, earning a passing score for structure despite its minimalism.

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 4 parameters with rich AWS API capabilities, no annotations, and no output schema, the description is insufficient. It lacks critical context such as the fact that all parameters are optional, what the response contains, or that this specifically targets DocumentDB instances (compatible with MongoDB) rather than RDS instances.

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%, with clear descriptions for profile, region, db_instance_identifier, and filters in the JSON schema. The tool description adds no additional parameter context beyond the schema itself, warranting the baseline score.

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 states the verb ('Describe') and resource ('DocumentDB instances'), providing basic clarity. However, it fails to distinguish from critical siblings like 'aws_docdb_describe_db_clusters' (clusters vs instances) or 'aws_rds_describe_db_instances' (RDS vs DocumentDB), which is essential given the 100+ AWS tools available.

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 tool versus alternatives like the cluster variant or RDS equivalent. Given that all 4 parameters are optional (0 required), the description should explicitly state that omitting filters returns all instances, but it does not.

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