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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value beyond them by describing the outward effect — real visitors begin receiving the message in the widget — which is a consequence the hints alone don't convey. It omits reversibility (that pause_proactive_message exists to undo it) and immediacy of the change.

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 sentence, front-loaded with the action and then the consequence, with no filler or restatement of the title. Every clause 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 publish/mutation tool with full annotation coverage, complete schema documentation of the confirm gate, and no output schema, the description supplies the key missing piece an agent needs: what publishing actually does to end users. Minor gaps remain around reversibility and whether the change takes effect immediately.

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 messageId and the confirm safety gate are fully documented in the schema itself. The description adds nothing about parameter meaning, format, or the confirm workflow, 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?

States a concrete verb and resource ("Puts a message live") plus the material effect (visitors matching the audience and pages start seeing it in the widget). It distinguishes this from pause/test implicitly through the effect, but never names the sibling operations (test_proactive_message, pause_proactive_message, update_proactive_message) that an agent must choose between.

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: the agent can infer this is the activation step for an already-created and targeted message. There is no explicit statement of when to use it rather than test_proactive_message or pause_proactive_message, and no prerequisites such as the message needing to be created first.

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