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

Annotations only declare the generic mutation profile (readOnly=false, destructive=false, idempotent=false, openWorld=true); the description adds real behavior: an email is actually sent to an address outside the platform, acceptance expires after 14 days, owner cannot be invited, and pending invitations consume plan seat quota. These consequences (external side effect, time-bound state, quota impact) are not derivable from annotations or schema.

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, zero filler, front-loaded with the action and then the constraints in decreasing order of importance (permissions, expiry, role limits, quota). Every sentence carries a distinct constraint.

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 3-required-param mutation with no output schema, the description covers permissions, external side effects, expiry, allowed roles, and quota impact — enough to call it correctly. It is silent only on edge cases such as what happens when the address already has a pending invitation, which is a minor gap given idempotentHint=false is already declared annotation.

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 100%, so the schema already documents all three parameters including the role enum constraint, and the description's role rule duplicates it. The description adds no syntax, format, or ID discovery guidance beyond the schema, so the 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?

"Invite a person to join an organization by email" gives a specific verb (invite), a specific resource (organization membership), and the mechanism (email), which cleanly separates it from the sibling delete-invitation-tool and from the create-*-tool family. An agent can identify the operation without opening the 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?

The description states the precondition (admin or owner rights in the organization) and the admission rule (allowed roles admin/member, owner cannot be invited), so an agent knows when the call will succeed. It does not name an alternative or say when not to use it (e.g., how to revoke — presumably delete-invitation-tool), so it stops short of routing guidance.

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