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

Annotations declare destructiveHint=true but the description goes further, adding the two facts the annotation can't convey: that the action is irreversible and that it is restricted to the original poster. Auth/permission needs and reversibility status are exactly the behavioral context this dimension rewards.

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, front-loaded clauses — action, then constraint, then the safety instruction — with no filler. Each sentence 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?

No output schema exists, so return values need not be explained. For a destructive single-target tool the definition covers purpose, permission constraint, irreversibility and the confirmation step — everything needed to invoke it 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 100%, so channel, ts and account are already documented and the description adds no parameter-level meaning. Baseline 3 applies when the schema carries parameter semantics.

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+resource ('Permanently delete a Slack message') and even names the underlying API (chat.delete). The word 'Permanently' implicitly distinguishes it from the sibling trash_message/delete_message_alert tools, so an agent can select it without opening a schema.

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 clear operating context: 'Only whoever posted it can delete it' establishes a permission precondition, and 'confirm with the user before calling' is explicit when-to-act guidance. It stops short of naming an alternative (e.g. trash_message for recoverable removal), so no explicit exclusion is offered.

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