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

Annotations already flag destructive=false... actually destructiveHint=true, idempotentHint=false, openWorldHint=true, so the safety profile is documented. The description adds genuine behavioral context beyond annotations: the PENDING-only precondition and the consequence that the post auto-publishes at the new time. It doesn't say what error results from a non-pending post, so not a 5.

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 tight sentences, front-loaded with the action, followed by the precondition and a warning. Every sentence earns its place with no redundancy.

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?

With no output schema, the description does not need to explain returns, and annotations cover the safety profile. It equips the agent with the key precondition and the auto-publish consequence, though it omits what happens on failure (error vs no-op), leaving one minor gap.

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 baseline is 3. The description adds no format or syntax detail about postId, publishAt, or timezone beyond what the schema already states, so it neither compensates nor detracts.

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: 'Replace the delivery time of a pending post.' This clearly differentiates it from siblings like update_recurring_post, publish_post, and delete_post. An agent can identify the operation without opening the 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 a clear precondition ('Only works on posts with status PENDING') which implicitly defines when-not-to-use, and adds a caution to confirm the post and time before calling. It does not explicitly name alternative tools (e.g. update_recurring_post for recurring posts), so it stops short of full routing guidance.

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