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

Annotations already declare destructiveHint=true and non-idempotent, so irreversibility alone would add little; the description goes further by explaining the shared-media lifecycle (a file used by several targets is deleted once, one still referenced elsewhere is kept) and the published-post limitation. It also discloses the required delete scope. The only gap is that it says nothing about the response or how failures surface.

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?

It is front-loaded with the destructive action and the routing rule, and nearly every clause carries information an agent needs. The long parenthetical about shared media interrupts the sentence flow and makes the opening harder to parse on a single read, but no sentence is 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 two-parameter destructive tool with no output schema, the description covers the things that matter: what gets destroyed, what is preserved, scope limitations for published posts, authorization requirements, and the correct alternative tool. An agent has everything needed to call it safely and 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%, with both id and sourceUrl documented in the schema itself, including provenance for id and an explicit 'never invent one' instruction for sourceUrl. The description adds no parameter-level meaning of its own, 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 opens with a specific verb and resource ('Permanently deletes a post and its media') and immediately scopes the behavior to media cleanup. It also names the sibling update_post and the boundary between them, so an agent can distinguish cancel_post from other post tools without reading schemas.

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 the positive trigger ('Only use it when the user asks to drop a post') and routes the alternative case explicitly ('to change the text or date, use update_post instead'). The caveat that already-published posts are removed from Broadcast only, not from the networks, further clarifies when this tool does and does not achieve the user's goal.

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