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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description usefully adds that this is a pre-flight eligibility check (send/delete/inbox capacity) rather than a data fetch, but says nothing about auth scope, rate limits, or whether it reflects live state.

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?

A single compact sentence with no filler. The phrasing is slightly awkward ('or whether another inbox fits'), but nothing is wasted and the checks are front-loaded.

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?

An output schema exists, so return values need not be described. Still, for a tool that aggregates permission and capacity state, the description is thin: it never enumerates which permissions or limits are reported, and its overlap with get_sending_policy/get_receiving_policy/get_outbound_quota is unresolved, which is the main thing an agent needs to disambiguate.

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?

The tool takes no parameters, so the baseline is 4. There is nothing for the description to clarify, and the empty schema with additionalProperties=false is unambiguous.

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?

The description says it checks whether sending/deletion is allowed and whether another inbox fits, which conveys the resource (account-level permissions/capacity) but uses a soft verb and never names the resource. It also does not differentiate itself from siblings that clearly overlap, such as get_sending_policy, get_receiving_policy, and get_outbound_quota, leaving the agent unsure which of these to call.

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 three checks imply a context (before sending, deleting, or creating an inbox), which is a reasonable hint at when to use it. However there is no explicit when-to-use statement, no prerequisites, and no guidance on choosing this aggregate over the granular policy/quota siblings.

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