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

Annotations indicate readOnlyHint, idempotentHint, and destructiveHint false, consistent with a read operation. The description adds useful detail about the managed_inbox_address field being a domain (not a mailbox) and clarifies that when non-null, the result includes sender_address. No contradictions.

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?

The description is two sentences, efficiently conveying purpose and key details about return fields. It is front-loaded with the primary use case. Minor redundancy in explaining managed_inbox_address could be condensed, but overall concise.

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?

Given the presence of an output schema (which handles return value details), the description adequately covers purpose, parameter usage nuance, and a specific field behavior. No obvious gaps for this simple read tool.

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 baseline is 3. The description adds value by explaining how the api_key parameter is conditionally required ('Only needed when this connection has no signed-in account: pass the api_key returned by createEmailAddress...'), which aids correct invocation beyond schema documentation.

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 clearly states the tool retrieves the authenticated Primitive account summary, listing specific fields (plan, onboarding state, managed inbox domain). It distinguishes itself from siblings by focusing on account-level information rather than email operations or domain management.

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 specifies when to use the tool ('when you need the authenticated Primitive account summary'). However, it does not explicitly state when not to use it or mention alternative tools for similar data, though context suggests it is unique among siblings.

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