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

Annotations only cover the safety triad; the description adds genuinely non-obvious context — that a generic link yields an owner-approval request rather than immediate access, and that the Space owner bears private usage cost so no subscription is required. Still silent on failure modes, idempotency, or what a pending approval looks like.

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 short sentences, each earning its place: action, parameter rule, then billing/approval caveat. Front-loaded and waste-free.

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 values need no explanation, and the description covers both invocation modes and cost implications. The remaining gap is workflow guidance — whether to preview first or what to do while approval is pending.

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 0%, so the description must carry the meaning of both parameters. It does: it explains what each identifier represents and enforces mutual exclusivity, compensating for the bare regex-only schema.

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+resource ('Accept a recipient-bound invitation') and covers the second mode ('request owner approval for a generic link'). The two-mode framing implicitly distinguishes it from private_space_approve_invitation (owner-side) and private_space_preview_invitation, though it never names them.

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 a clear selection rule: one of the two parameters, not both, and maps each parameter to its scenario (recipient-bound vs generic link). It stops short of naming alternatives such as preview_invitation or list_invitations, or stating exclusions.

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