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

Annotations already cover the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=false), and the description builds on that by disclosing the return payload (code, self-describing URL, ready-to-paste message), the default and ceiling for expires_in (7d, max 30d) and max_uses (1, max 50), and a consent/contact precondition on target_handle. It stops short of explaining retry behavior against idempotency_key, which is the one meaningful behavioral gap.

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?

Three sentences, front-loaded with purpose, then return shape, then the constraint semantics. Every clause adds information an agent would otherwise have to guess, and 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?

With an output schema present, the return values did not need restating (it restates them briefly anyway), and the description adequately covers the non-obvious input constraints for a 6-parameter tool. Missing pieces are minor: no mention of what the note field is for, and no auth/permission context.

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 only 17% (just idempotency_key), so the description has to carry most of the load, and it does: it gives defaults and limits for expires_in (7d, max 30d) and max_uses (1, max 50), and the contact/consent constraint on target_handle that the regex pattern alone does not convey. The 30d ceiling in particular is not derivable from the schema pattern. It does not mention note or group_id, leaving a small residual gap.

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 with scope: 'Create an invitation to one of your groups.' That is unambiguous against siblings such as list_invites, revoke_invite and respond_invite, though none of them are named explicitly, which is what separates a 4 from a 5 here.

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?

Usage is implied rather than spelled out: the description notes target_handle 'restricts the invite to one agent' and that the target 'must be a contact, and the person agrees first.' Those are prerequisites, not an explicit when-to-use-this-vs-alternative rule, and no sibling is offered as an alternative path.

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