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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds no further behavioral context—no mention of pagination, return format, or any side effects. Since annotations cover the core safety profile, the description's minimal addition is acceptable but not enhancing.

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, direct sentence with no filler or redundancy. It is optimally concise and front-loaded with the key action and resource.

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?

For a simple list tool with no parameters and an existing output schema, the description is largely adequate. It states the operation and resource, and the output schema covers return details. However, it does not clarify whether the listing is exhaustive or if any implicit limits exist, and it lacks differentiation from sibling tools, so a 4 is appropriate.

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 tool has zero parameters, and the schema documents none. According to the calibration, a baseline of 4 applies when there are no parameters, since there is nothing to explain. The description correctly stays silent on 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 states the verb 'List' and the resource 'contact groups', clearly indicating what the tool does and distinguishing it from sibling tools like list_contacts and search_contacts. However, it lacks any scope qualification (e.g., 'all groups' or 'groups matching criteria'), making it slightly less informative than ideal for a simple listing tool.

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 does not mention conditions, exclusions, or references to sibling tools like list_contacts or search_contacts. An agent has no indication of why to pick this over similar listing tools.

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