Add people to a group

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

The description adds meaningful behavioral details beyond the annotations: each result indicates success, and contacts who cannot be added directly yield an invite code. It also highlights an authorization constraint, 'the account administers.' This is useful context that the annotations (readOnlyHint, openWorldHint, idempotentHint, destructiveHint) do not provide.

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?

Two sentences, no filler, with the core action front-loaded and the behavioral nuance following immediately. Every sentence contributes value.

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 full schema, annotations, and lack of output schema, the description covers purpose, permission scope, and response behavior enough for an agent to call it correctly. It would be slightly stronger with an explicit note on partial success semantics or already-existing members, but the per-result phrase largely covers partial success.

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%, and each parameter already has a descriptive schema entry (e.g., groupId from list_groups, contactIds E.164 format). The description does not add parameter-level meaning, so the baseline score of 3 applies.

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 a specific action, 'Add participants to a group', with the resource 'group' and a scope qualifier, 'the account administers'. It clearly distinguishes itself from sibling tools like remove_group_participants or promote_group_participants through the verb 'add' and the invite-code fallback behavior.

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?

Usage is implied: the tool is for adding participants to a group, and the prerequisite that the account must administer the group is explicit. However, it does not reference alternatives or state when not to use it, leaving sibling differentiation to the agent.

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