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

Annotations already cover the safety profile (readOnly=false, idempotent=true, destructive=false, openWorld=false), so the bar is lower; the description still adds an authorization constraint ('only the opposite side') and a semantic boundary ('does not imply task success') that annotations cannot express. It omits the concurrency behavior implied by the required expected_message_version, which is the notable remaining gap.

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 short sentences with zero filler; the core action is front-loaded and the two clarifiers follow in priority order. Nothing could be cut without losing a distinct piece of information.

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, five fully undocumented required parameters, and a version-guarded mutation, the description leaves out what a caller most needs: how expected_message_version interacts with a conflict and what the agent should do on mismatch. What is present is accurate but insufficient for a tool of this complexity.

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 five required parameters, so the description must carry the load and does not. It restates the receipt values that are already in the enum, and adds no meaning at all for expected_message_version (optimistic-concurrency token), idempotency_key, message_id, or conversation_id.

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?

States a specific verb and resource ('Acknowledge a received message') and immediately names the two receipt states, delivered or read. An agent can distinguish this from send_conversation_message or the outcome tools, though no sibling is named explicitly.

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?

Gives a real precondition plus a negative: 'Only the opposite side can acknowledge' tells the caller when it is authorized to use this tool at all, and 'this does not imply task success' steers away from confusing it with submit_outcome/complete_conversation_draft. Missing only an explicit statement of when to prefer this over other conversation tools.

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