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

The description advertises a create (write) capability while the annotations declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. This directly contradicts the structured safety profile. Additionally, it discloses nothing about pagination behavior or rate limits beyond the boilerplate pricing note.

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 core is a single sentence, but it merges two unrelated operations into one clause, and the injected aisa-pricing HTML block adds non-selection-relevant clutter. The payload is not front-loaded around a single clear capability.

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?

Although an output schema exists (so return structure need not be described), the definition is incomplete: it leaves the create-vs-list ambiguity unresolved, omits create parameters the schema does not have, and contradicts its own annotations. For a tool surrounded by many near-named siblings, this is insufficient to call correctly.

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% and the three actual parameters (limit, ascending, page_token) are self-documented. The description instead names 'custom username, domain, and display name' as inputs, none of which exist in the schema, so it misleads rather than adds meaning about the real parameters.

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 leading clause states a clear verb+resource ('Retrieve a list of inboxes with pagination support'), which matches the tool name and the read-oriented siblings. However, it then appends 'or create a new inbox', conflating two distinct operations and blurring the tool's identity against siblings like get_agentmail_inbox (singular) and post_agentmail_inbox (the real create path). An agent cannot cleanly tell what this tool does from the description alone.

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 mentions pagination support but gives no conditions for choosing this tool over get_agentmail_inbox, get_agentmail_inbox_messages, or the dedicated create endpoints. There is no when-to-use, when-not-to-use, or alternative routing guidance.

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