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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds the full behavioral picture: validation, the Action Gate check, non-posting conditions (unpaid, missing DATABASE_URL, stop, timeout), the webhook dependency, and the resulting stop when the webhook is absent. This is far beyond what the annotations convey.

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?

The 'Write Gate' label is front-loaded and each sentence carries workflow information. It is dense and slightly long-winded (the $49 seat/pricing line is marginal), but no sentence is pure filler.

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 gated write tool with no output schema, the description covers the decision states and side effects thoroughly. Minor gap: it does not describe the returned payload shape for a successful post, though the decision vocabulary (go/wait/stop) is explained.

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 all five parameters are already documented, including approval_id's provenance ('From a previous wait'). The description reinforces approval_id's reuse pattern but adds no syntax or format detail beyond the schema, 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?

The description states a specific verb and resource ('posts' to Slack) plus the gating condition ('only when the decision is go'), and names the sibling tools it depends on (check_action, get_approval). An agent can distinguish it from check_action or get_approval at a glance.

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 explicitly when to call (after a go decision), what to do on a wait decision (poll get_approval, then re-call slack.post with approval_id), and the failure conditions that should not result in a post. Alternatives and sequencing are named, not inferred.

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