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

Annotations already declare destructiveHint=true, non-idempotent, and open-world, so the description does not need to re-state the safety profile. It adds genuinely useful behavior: the new item is always a draft, Substack prepends [COPY] to the title, and nothing is published or sent. That last point reassures without contradicting the destructive annotation, which correctly reflects that a new resource is created.

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 short sentences, front-loaded with the core action, followed by field scope and the one surprising behavior ([COPY] prefix). Every sentence carries information the agent would otherwise have to discover by trial.

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 simple one-parameter mutation with no output schema, the description is complete: it covers what is produced, which fields are copied, the title side effect, the follow-up tool for renaming, and the non-publication guarantee.

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?

The single parameter has 100% schema coverage and is documented there as the post ID from list_posts. The description names no parameters and adds no syntax or format beyond the schema, so baseline 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?

States a specific verb and resource ('Copy any post into a new draft') and distinguishes the result from a blank draft by describing exactly which fields carry over. An agent can tell this apart from create_draft without opening either 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?

Clear context: use this to replicate an existing draft or published post, with an explicit follow-up pointer to update_draft for renaming. It does not explicitly say when to prefer create_draft instead, but the copy semantics make the boundary obvious.

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