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

Annotations only declare the safety profile (readOnlyHint=false, destructiveHint=false), and the description adds real behavioral context beyond them: no guest access, the permission model, server-side credential handling, and that mailbox passwords and message content are never returned. No disclosure of what happens if a destination mailbox does not exist, which keeps 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, front-loaded with the create action and scope, then constraints. Nothing is padded, though the permissions/security sentences read as a list of statements rather than a tightly integrated explanation.

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 5-required-parameter mutation with no output schema, the description covers authorization and confidentiality well, but never says what a successful call returns (e.g., an alias identifier) nor how failures are surfaced, leaving an agent to guess at the result shape.

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 all five required parameters are already documented. The description adds no parameter-level detail beyond the schema (no naming rules for local_part, no idempotency_key semantics), 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?

States a specific verb and resource ('Create an alias to existing mailboxes in this organization'), which cleanly separates it from sibling lifecycle tools like commsharbor_email_alias_update, _suspend and _resume. It does not name a sibling explicitly, so it falls just short of 5.

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 usable context: destinations must be existing mailboxes in the organization, guest access is excluded, and the permission tiers (members read; owners/admins/org keys manage) tell an agent whether the caller is eligible. However, it never states when to prefer this over alias_update or what preconditions (e.g., verified domain) must hold, so guidance is implied rather than explicit.

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