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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes beyond them by disclosing the critical behavioral trap: narrated silence text ('*(Staying silent…)*', 'Internal:…') is delivered to the guest verbatim, so this tool is the only safe way to stay silent. It also notes the reason field is retained for admin audit.

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 sentences, tightly front-loaded: the action first, then use-cases, then the failure mode being warned against. Every sentence carries distinct, non-redundant 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?

For a no-op control tool with full schema coverage and a rich annotations block, the description supplies everything needed to call it correctly: what it does, when to invoke it, and why substituting text is harmful. No output schema is needed for a tool that by definition sends nothing.

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% and the schema already explains both parameters in detail (reason stored in trace_tool_executions.tool_params; in_workspace semantics). The description adds no parameter-level detail beyond what the schema provides, so the baseline of 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 states a specific verb and effect ('End this turn without sending any message'), which is unambiguous and clearly distinct from siblings like messages_send or job_escalate. An agent can immediately tell this is the silence/no-op path, not an outbound-message tool.

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 enumerates explicit when-to-use conditions (thread owned by a human after job.escalate, guest self-resolving, duplicate message, observation-only turns) and names the wrong alternative (narrated silence text). Nothing is left to inference.

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