add_participant

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

Annotations already declare idempotentHint=true and destructiveHint=false; the description reinforces idempotency and adds genuinely new behavioral context: the moderator-rights requirement and the constraint that one-to-one and note-to-self conversations take no participants. This is useful auth and edge-case disclosure beyond the structured hints.

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?

Front-loaded one-line summary, then structured Args/Returns blocks. Given three undocumented parameters and five source modes, every sentence earns its place; there is no filler.

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?

Covers prerequisites, idempotency, per-source semantics, and conversation-type exclusions; output schema exists but the description still points to get_participants for attendee IDs. Nothing needed to invoke this mutation correctly is missing.

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 0%, so the description carries the full burden and does it well: it explains token, enumerates every participant format, and documents all five source values including default and side effects ('groups' adds every member, 'emails' invites a guest). This substantially exceeds what the bare schema provides.

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 ('Add someone to a conversation') that is clearly distinct from neighboring tools like add_circle_member, remove_participant, and set_participant_role. An agent can identify the target operation without opening the schema.

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?

Gives real preconditions ('Needs moderator rights') and an operational caveat ('adding someone twice changes nothing'), plus per-source guidance on which source value to pick. It stops short of naming alternatives or when-not-to-use cases (only the one-to-one/note-to-self limitation is stated).

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