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

The annotations already declare readOnlyHint=true, so the read-only nature is established. The description adds that the listing returns id, name, and description, which is helpful. It does not disclose other behaviors such as pagination, ordering, or whether the list may be incomplete, but this is minor given the simple read-only nature.

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 two sentences with no wasted words. The primary action and output are front-loaded, and the second sentence provides a practical downstream usage tip. It is compact and fully earns its length.

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 zero-parameter list operation with readOnlyHint, the description covers what the tool returns and why the results matter (for creating contacts). It does not describe pagination or ordering, but these are not likely essential for such a simple list. The description is complete enough for an AI agent to use the tool correctly in most cases.

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, so there is no parameter meaning to convey. The baseline for 0 parameters is 4, and the description correctly focuses on the output rather than parameters. No additional parameter semantics are needed.

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 the resource ('contact groups (contact lists) in the CRM'), and specifies what each result contains ('id, name and description'). This is specific and unambiguous, even though there are no sibling tools to differentiate from.

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 gives an implicit usage context by noting 'Use a group id when creating a contact,' which suggests this tool is the way to obtain group IDs. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any exclusions or prerequisites. The guidance is implied rather than direct.

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