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

The annotations already declare destructiveHint=true, so the description does not need to carry the full safety burden. It adds value by clarifying that an empty media_id removes the featured image, but it does not explain that setting a new image replaces the existing one or detail permissions/reversibility.

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?

The description is a single, front-loaded sentence with no wasted words. It immediately states the primary action and then the conditional removal behavior.

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 two-parameter mutation with annotations covering safety, the description is adequate but not complete. It omits that setting a featured image overwrites any existing one and gives no handling details for invalid media IDs, though no output schema exists to explain return values.

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 0%, so the description must compensate. It identifies post_id as the post whose featured image is set and explains media_id as a Media Library item with the special empty-value removal behavior, but it does not fully document the parameters beyond these points.

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 states a specific verb ('Set') and resource ('featured image of a post'), plus the removal case when media_id is empty. It is clear what the tool does, though it does not explicitly distinguish itself from siblings like wp_update_post or wp_alter_post.

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 implies the operation and gives a useful condition for removal when media_id is empty, but it does not state when to use this versus alternatives such as wp_update_post, nor does it mention prerequisites.

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