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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is partly covered. The description still adds real value by disclosing that queueing is asynchronous ('Queued is not delivered') and by naming gating requirements (budget, share confirmation). It does not explain what the destructive hint actually consumes or how budget is spent.

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?

Three short sentences with zero filler; the core action and the 'queued, not delivered' caveat are front-loaded and no sentence is redundant.

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 7-required-parameter mutating tool with 0% schema description coverage and no output schema, the description is far too thin. It never explains what materials or versions mean, why text and idempotency_key are required, or what a queued message's lifecycle looks like, so an agent lacks what it needs to invoke this 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 description coverage is 0% across 7 required parameters, so the schema provides no semantic help and the description must carry the burden. It only loosely gestures at 'share confirmation' (share_approved) and skips text, materials, idempotency_key, client_message_id, and expected_conversation_version entirely, leaving most parameters semantically opaque.

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 gives a specific verb+resource ('Queue a shared message') and scopes it ('within the owner's explicitly bounded conversation grant'), which is more than a restatement of the title. It is distinguishable from siblings like ack_conversation_message or complete_conversation_draft, though it never explicitly contrasts with them.

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?

It states preconditions for a successful call ('current automatic mode, remaining message budget and share confirmation'), which implies when the tool is usable. However, it offers no guidance on when to choose this over sibling tools such as complete_conversation_draft, nor any when-not-to-use condition.

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