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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation profile is known. The description adds real value by narrowing the destructible state set (unpublished, unexported posts) and clarifying that YouTube-side removal is out of scope. It says nothing about reversibility, whether queued exports or credits are affected, or what an error looks like if the post has already gone out.

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 tight sentences with zero filler. The positive scope comes first and the exclusion second, which is the right order for an agent deciding whether to call it.

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, non-open-world destructive mutation with no output schema, the definition covers purpose, valid state, and the main edge case. Minor gaps remain around post-condition behavior (is the cancellation reversible, what happens to a pending export), but nothing essential to invoking it correctly is missing.

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?

There is a single parameter and schema description coverage is 100%, with the schema even explaining provenance ('The post id post_video returned'). The description adds no parameter-level detail, which is acceptable given the schema does the work, but means no credit above baseline.

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 and resource ('Cancels a post') plus a precise applicability boundary: only posts that have not gone out yet, including ones 'waiting for its export'. The second sentence draws a line against the YouTube-removal case, though no sibling tool is named, so differentiation is conceptual rather than explicit.

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?

The description tells the agent when this tool applies (scheduled or pre-export posts) and when it does not (already-published YouTube videos, which must be removed on YouTube). It stops short of naming the specific sibling to use for the published case, leaving that routing to inference.

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