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

With no annotations provided, the description must disclose behavioral traits, but it only mentions the auth requirement ('Requires an admin owner_key') and the action. It does not state side effects (e.g., sending an email), reversibility, failure modes, or response format, which is a significant gap for a mutating tool.

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 a single, front-loaded sentence that states the core purpose before the requirement. There is zero wasted verbiage, and every word earns its place.

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?

Despite the simplicity (2 params, full schema coverage), the description lacks behavioral context that the schema cannot provide, such as expected outcomes, error conditions, or whether the invitation is immediately effective. Without annotations or an output schema, an agent is left guessing at the tool's side effects, making the description incomplete for a mutating tool.

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?

The input schema already provides 100% coverage for both parameters, including the default behavior of owner_key. The description adds no additional parameter meaning beyond restating the admin requirement, which is already in the schema. Baseline 3 is appropriate since the schema carries the detailed semantics.

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 verb 'Invite' and the resource 'an email', with the target 'your account'. It distinguishes the tool from siblings like send_email_reply or register_client, leaving no ambiguity about what it does.

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?

No guidance is given on when to use this tool versus alternatives, nor any exclusions or prerequisites beyond the admin owner_key. The description does not mention scenarios where another tool would be more appropriate, leaving the agent to infer usage from the purpose alone.

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