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

Annotations only give the safety/idempotency profile; the description goes well beyond: nothing is shared until acceptance, repeat calls return the existing invitation with no second email, an email is sent on acceptance, and list_workspaces reveals whether the invitee has joined. It also discloses the billing consequence (30 days free, then $19/30 days) that an agent might otherwise trigger unknowingly.

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?

Front-loaded with the core action and consequences; nearly every sentence carries operational value (idempotency, withdrawal, exclusion, acceptance visibility). Somewhat dense as a single block, and the pricing sentence plus docs link are the least essential parts, but nothing is wasted.

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 mutating, email-sending, idempotent tool with no output schema, the description covers the effect, the pending-state semantics, idempotency, how to undo, side effects, and how acceptance is observable. An agent has everything needed to call it and predict the outcome.

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 100%, so email, namespace_prefix, and note are already documented with their constraints and examples. The description reinforces that the prefix is read-write and per-account but adds no syntax or format detail beyond the schema; baseline 3 applies.

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 (invite), actor scope (one person, by email), resource (namespace prefix of THIS account) with a concrete example (project:barn). It is clearly distinguishable from siblings like list_invites, accept_invite, and revoke_grant, which are named in their respective roles.

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?

Explicitly describes the follow-up flow on the recipient's side (list_invites and accept_invite), the withdrawal path (revoke_grant with grant_id), and a hard exclusion: not available from a shared workspace session. Named alternatives plus a when-not condition.

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