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

Annotations already declare destructiveHint=true and openWorldHint=true, so the safety profile is covered. The description adds the existing-member precondition, the default access level, and the 422 failure conditions, which is meaningful context beyond the annotations. It does not state that an invite email is dispatched as a side effect, which would be the remaining useful disclosure.

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?

Four short sentences, front-loaded with the action, then requirements, defaults, failure modes, and a docs link. No filler or redundancy.

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?

An output schema exists, so return-value description is unnecessary, and the description covers inputs, defaults, and error conditions. The only modest gap is not flagging the email-send side effect, which matters for a destructive/open-world mutation.

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?

With reported schema description coverage at 0% and a nested body/invitation wrapper, the description compensates by naming the two required sub-fields and noting access defaults to standard. It does not clarify the nested body wrapper shape or the admin/standard enum trade-offs, but it covers the decision-relevant parameters.

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 ('Invite a user by email') and names the mechanism (email) and the key identity fields. No sibling tool creates invitations, so differentiation is unambiguous against list-invitations/get-invitation.

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 preconditions: invitation.email and invitation.inviter_email are required, and inviter_email must be an existing member. Adds error semantics (422 when email is missing, inviter invalid, or the address is already a member), which tells the agent when a call will fail. No explicit when-not-to-use or alternative tool, so it stops short of a 5.

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