add_group_members

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

The annotations already indicate destructiveHint=true, and the description adds one useful behavioral fact: adding an existing member has no effect, implying idempotence. It does not disclose permissions, failure behavior, or whether the group must already exist, so it contributes a moderate amount 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?

Three concise sentences with no filler. The main action is front-loaded, followed by the input preparation hint and an idempotence note; every sentence serves a clear purpose.

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 two-required-parameter mutation with no output schema, the description provides enough to select and invoke the tool correctly: the action, how to resolve member IDs, and duplicate-member behavior. It omits error and permission details, but those are not essential for basic use.

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 coverage is 100%, so the baseline is 3. The description adds meaningful context by clarifying that members are user IDs and by directing agents to lookup_user for resolving names or emails, which goes beyond the bare schema property descriptions.

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 operation ('Add one or more users to a group') and the resource being modified. It is distinct from siblings like remove_group_member or list_group_members by naming the exact mutation and specifying that members are user IDs.

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?

It gives a concrete preparatory instruction: 'Use lookup_user to find user IDs by name or email.' However, it does not explicitly state when to choose this tool over alternatives such as remove_group_member, so the usage context is more implied 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.