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

The description discloses side effects (sends invitation emails) and error behavior (conflict if address already exists). It clarifies the tool is for manual invites, not IdP-managed orgs. While the annotation destructiveHint=true is not explicitly explained, the description adds context that the main side effect is sending emails, which is consistent with a mutating operation. No contradiction.

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 concise and front-loaded with the core purpose. It includes usage guidance and side effects in a logical order. It avoids unnecessary repetition and is appropriately sized for the tool's complexity.

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?

The description covers purpose, usage context, side effects, and error handling. Since there is an output schema, return value details are not needed. The tool has one parameter, and the description provides sufficient context for an agent to decide when and how to use it.

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 schema covers the emails parameter with description and example, and the tool description repeats the example and adds the 'max 10 per call' constraint, which is not in the schema. This adds value beyond the schema, though the schema already provides basic 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 action (invite), the resource (people to corporate Fax.Plus account), and the method (by email). It specifies a limit of 10 per call and explicitly names resend-invitations as an alternative, distinguishing its purpose from siblings.

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 provides explicit guidance: use resend-invitations for pending invites that have not joined, and use the IdP for identity-provider-managed orgs. It states that manual invites are for orgs not using SCIM/SAML, so the agent knows exactly when to use this tool vs alternatives.

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