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

Adds meaningful context beyond annotations: an actual email is dispatched, MANAGE_USERS is required, 201 is returned on success, and the API-key scope is `users:write`. Annotations already flag destructive/openWorld/non-idempotent, so the description complements rather than repeats them; it could still warn that repeat calls re-send mail to the invitee.

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 dense sentences, front-loaded with the action, then the parameter gotcha, then permissions/return/scope. No filler and no repetition of schema text.

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 mutation that triggers outbound email with no output schema, the description covers auth, id resolution, success code, and scope. Minor gap: it says 'current workspace' though a `workspace` parameter overrides it, and duplicate-invite behavior is unstated.

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 baseline would be 3, but the description adds genuine disambiguation: `workspaceAccessLevelId` is a numeric Long id and NOT a role name like "admin"/"member", plus the endpoint to translate names to ids. That is the single most likely invocation error and it is called out explicitly.

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?

Specific verb+resource: 'Send an email invitation to join the current workspace.' An agent can distinguish this from pm_list_invitations and pm_cancel_invitation. It does not, however, contrast it with pm_add_workspace_member / pm_add_team_member, which are the plausible alternatives for getting a user into a workspace.

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 pre-call conditions: caller needs MANAGE_USERS permission, and the access level must be resolved via /v1/workspaces/{ws}/access-levels before calling. It stops short of stating when to prefer an invite over a direct add-member call, so it is clear context without explicit exclusions.

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