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

Adds real value beyond the annotations: it discloses the fee refund and the window after which cancellation fails, neither of which appears in readOnlyHint/destructiveHint/idempotentHint. It does not explain what happens on a failed cancel (error vs. silent no-op) or that the refund only occurs once, which matters given idempotentHint=false.

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 short sentences, zero padding, with the refund benefit and the deadline both front-loaded. Nothing here could be cut without losing information.

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?

An output schema exists, so return shape needn't be described, and the description covers the critical precondition and side effect. The remaining gap is failure behavior when the item has already been decided, which is the most likely error an agent will hit.

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 coverage is 100% with a single documented parameter, so the baseline is 3. The description adds only that the id refers to a queued message; no format, lookup, or validation detail beyond the schema.

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?

Uses a specific verb (withdraw) and a precisely scoped resource (a message still queued for moderation), which separates it from the sibling delete_post that presumably handles already-decided posts. The one wrinkle is terminology: the schema calls the parameter a 'post id' while the description says 'message', a minor mismatch an agent must reconcile.

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 an explicit precondition (still queued for moderation) and an explicit exclusion (too late once moderation has decided), which is exactly the timing test an agent needs. It stops short of naming the alternative tool to use once moderation has decided, leaving that inference to the agent.

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