Get mailbox message

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

Annotations already provide a rich safety profile (readOnlyHint, idempotentHint, non-destructive), so the bar is lower. The description adds genuine value beyond those hints by disclosing that reading does not trigger the mailbox's claim/acknowledgment state machine — a subtle workflow behavior a generic readOnlyHint would not convey. No contradiction with annotations.

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 13-word sentence front-loads the verb and resource, then spends its remaining words on the critical differentiator ('without claiming or acknowledging it'). There is zero filler, and every word earns its place.

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 simple single-message read tool, the definition is complete: annotations cover the safety profile, the output schema covers return shape, the schema covers both parameters, and the description covers the one non-obvious behavioral nuance. Nothing an agent needs to invoke this correctly is missing.

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 both message_id and response_format are already fully documented with type, pattern, enum, and description. The description's mention of 'JSON payload' slightly reinforces the response_format parameter but adds no meaning beyond what the schema provides, 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?

The description uses a specific verb ('Read') with a precise resource ('one mailbox message and its JSON payload') and immediately distinguishes itself from claim_message and ack_message by stating it operates 'without claiming or acknowledging.' This makes the tool's purpose unambiguous and easily separable from all nine siblings without opening the schema.

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 phrase 'without claiming or acknowledging it' gives clear context that this is the side-effect-free inspection tool, implicitly routing claim_message and ack_message use cases elsewhere. It does not explicitly name those alternatives or state when-not-to-use conditions, but the context is strong enough that an agent can select correctly.

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