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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: the return contents and, importantly, that it returns null when the message has left the queue — a critical edge case an agent must handle.

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?

Two tight sentences: what it returns first, then the null edge case. No filler, no restatement of the title, and the most decision-relevant fact (null when no longer queued) is placed at the end where it reads as a caveat.

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?

With no output schema, the description carries the return-shape burden and does so adequately by listing content, estimated send time and allowed actions, plus the null case. Minor gaps remain around what "preparing" means and how invalid or unknown IDs are surfaced.

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 0% and messageId is nested under a params wrapper with no explanation in either schema or description. The description says nothing about the identifier (format, where it comes from, whether it must be a queued message ID), so it does not compensate for the coverage gap beyond the self-evident name.

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 states a specific verb and resource ("Returns one queued or preparing message") and enumerates the payload (content, estimated send time, allowed actions), which distinguishes it implicitly from the plural listQueuedMessages sibling. It never names a sibling explicitly, so differentiation is inferable rather than stated.

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?

Usage is only implied: an agent can infer this is the single-message fetch by ID, and the null case hints at polling or verifying queue state. There is no explicit guidance on when to prefer this over listQueuedMessages or getQueuedMessageEditSession, and no stated prerequisites.

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