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

Annotations already declare destructiveHint=true and non-idempotent, so the safety profile is covered. The description adds real value beyond that by disclosing a hard state precondition: the operation silently cannot succeed once the post has been published. It does not say what happens on failure (error vs no-op) or whether a cancelled slot is freed.

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?

Two sentences, zero filler, and the applicability constraint is front-loaded before the failure case. Every 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?

For a one-parameter destructive tool with full annotation coverage and no output schema, the description covers the key precondition and the main failure mode. It could be slightly more complete by stating what the caller receives on success/failure, but the essentials are there.

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 single parameter is well documented, including the accepted id forms (submission id, post id, or user-visible '#4'). The description adds nothing beyond the schema, so baseline 3 is appropriate.

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 uses a specific verb ('cancels') and a clearly scoped resource ('a post that has not gone out yet'), so an agent can tell this is a pre-publication cancellation. It does not explicitly distinguish itself from close siblings like delete_post, update_schedule, or cancel_campaign_posts, which is the only thing keeping it from a 5.

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 gives a clear usage condition (post not yet sent) and an explicit exclusion (already-published posts cannot be cancelled, because 'the platform has it and we do not'). It stops short of naming an alternative route for published posts (e.g. delete_post) or for editing instead of cancelling (update_schedule).

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