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

Goes well beyond the annotations (readOnly=false, openWorld=true, destructive=false): it discloses that an external email is sent to a third party, that re-invoking is idempotent-but-resends, that confirmation is on by default and can be toggled, and that a Cotlet API key with app access is required. This is exactly the kind of side-effect and permission context annotations cannot carry.

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?

Purpose is front-loaded and the sentences are individually useful, but it is slightly verbose — the confirmation-default clause and the 'Reaches other people' line overlap in intent, so a little trimming is possible.

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 mutation tool with no output schema, it covers the essentials an agent needs: what is created (a session participant), the external side effect (email to a third party), idempotency behavior, the confirmation gate, and the credential requirement. Nothing critical 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 coverage is 100% and each parameter is already documented (role enum with default, email, session_id source). The description restates the guest default but adds no syntax or format detail beyond the schema, so baseline 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?

States a specific verb and resource: it sends a studio invite email and adds one person to a scheduled session, with the recipient types (guest, producer, audience) spelled out. An agent can clearly distinguish it from read-only siblings like riverside_get_invite_links or riverside_list_sessions.

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 clear operating context: role defaults to guest, re-inviting the same email resends, and you must confirm with the user before each call because it reaches other people. It stops short of naming sibling alternatives (e.g., when to use this versus get_invite_links), so it is not a full 5.

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