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

Goes well beyond the annotations by disclosing trial duration, quota, that outgoing SMTP and external forwarding are disabled, role-based access (members read; owners/admins/org keys manage), guest access exclusion, and a security guarantee that the service credential and mailbox passwords/content are never returned. It does not explain what happens on re-invocation, which is notable given the required idempotency_key alongside idempotentHint=false.

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-loads the core action, duration, and quota before the constraints, and every sentence carries information. It is a dense single paragraph with security and permission clauses that are useful but slightly tangential to invocation.

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 with no output schema, the description covers effect, limits, prerequisites, and side effects thoroughly. The one missing piece is idempotency behavior: a required idempotency_key is never explained, and annotations declare idempotentHint=false, which an agent cannot reconcile from the text.

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% for both parameters, so baseline is 3. The description adds organizational context ('new workspace', 'operator-proved native quota') but no syntax, format, or meaning for organization_id or idempotency_key beyond the schema.

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 ('Start') plus a precisely bounded resource: 'the free receive-only Trial for 7 days, once per organization'. The receive-only scope and 7-day/1 GB limits immediately distinguish it from sibling provisioning tools like commsharbor_email_workspace or commsharbor_email_service_request.

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 preconditions - 'once per organization', 'Requires a new workspace and operator-proved native quota' - which tell the agent when the call will succeed. It does not name an alternative tool or an explicit when-not-to-use case, so it stops short of a 5.

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