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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), so the description's job is to add context — and it does: 7-day invitation expiry, re-invite behavior (fresh email), and the admin/paid-plan authorization requirement. It does not describe failure modes or what the email contains, keeping it from a 5.

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, each carrying distinct information (action, expiry, repeat behavior, authorization) and front-loaded with the core action. Nothing is redundant with the title or annotations.

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?

For a 2-parameter mutation with an output schema and full annotation coverage, the description supplies the non-obvious behavior (expiry window, re-invite semantics, plan/admin gating). Only marginal items such as failure behavior or scope of the target workspace are absent.

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 coverage is 50%: idempotency_key is well documented in the schema, while email relies only on format/maxLength with no description. The tool description adds nothing about either parameter (no email normalization, no retry-key guidance), so it does not compensate for the gap, but the covered half and the self-evident email field keep this at minimum viable.

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: 'Sends an email invitation to join the workspace as a member.' No sibling tool performs invitations, so an agent can distinguish this from list_members, add_competitor, or create_share_link without opening any schema.

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 real usage constraints — 'Admin only, on a paid plan' — which an agent must check before invoking. However, it never states when not to use it or points to an alternative (e.g., a direct-add-member path), so guidance stops short of the when/when-not/alternatives bar.

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