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

Annotations already declare destructiveHint=true and readOnlyHint=false. The description adds the explicit confirmation requirement and a side-effects statement, which goes beyond the annotations and reinforces the destructive nature. The side-effects line is somewhat redundant but still provides clear behavioral framing.

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 short and front-loaded with the purpose. The 'Side effects: deletes contact group' line is somewhat redundant with the first sentence and the destructiveHint annotation, so there is minor waste. Overall, it is efficient and easy to parse.

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 low-complexity delete tool with a full input schema, an output schema, and clear destructive annotations, the description is nearly complete. It communicates the required confirmation and the destructive side effect. It could additionally mention irreversibility or that contacts in the group are unaffected, but these are minor omissions.

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 both parameters already clearly documented: group_id and confirmation_text. The description adds no new parameter-level detail beyond saying confirmation is required, which the schema already captures. Baseline 3 is appropriate because the schema carries the semantic weight.

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?

States a specific verb and resource: 'Delete a contact group (Fax.Plus tag).' The clarification that a contact group is a Fax.Plus tag helps distinguish this from delete-contact and update-contact-group. It is unambiguous and directly aligned with the tool's name and title.

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 conveys that this is destructive and requires explicit confirmation, which gives the agent a clear operational constraint. However, it does not explicitly mention when not to use it or suggest alternative tools such as update-contact-group for non-destructive changes. Usage is implied rather than fully spelled out.

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