aggregate

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

Annotations already indicate read-only, idempotent, and non-destructive behavior, and the description is consistent with these. However, the description adds no extra behavioral context such as return type, potential performance implications, or pipeline limitations, which would be useful beyond the annotations.

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 sentence with no filler, directly stating the core functionality. It is front-loaded with the action and resource, making it immediately clear what the tool does.

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 simplicity of the tool and the presence of annotations and complete schema, the description is adequate but not rich. It does not mention return values or explain pipeline structure, but for an aggregation tool this is not a critical omission.

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?

The schema provides descriptions for all three parameters (collection, pipeline, limit) with 100% coverage, so the description adds no additional meaning. The baseline is 3, and no extra semantic detail is provided.

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 (run) and the resource (an aggregation pipeline on a MongoDB collection). It distinguishes from siblings like find by focusing on the pipeline execution, though it doesn't explicitly contrast with find or other read tools.

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 is given on when to use aggregation versus alternatives such as find, distinct, or count. The description does not specify scenarios where an aggregation pipeline is preferred or mention any exclusions.

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