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

Beyond the annotations (which only say readOnly=false, idempotent=false, destructive=false), the description discloses the real side effects: upvotes transfer with double-voter deduplication, the duplicate is hidden as merged rather than deleted, and the author is shown the destination. It also adds the auth requirement ("organizer key"), which no structured field captures.

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?

Dense but well front-loaded: purpose, then body shape, then effects, then constraints, then auth. The opening "Ideas and nominations:" duplicates the title and the inline body-shape notation is slightly cryptic, but no sentence is wasted.

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 three-parameter mutation with no output schema, it covers outcomes (merge, hidden post, author notification), preconditions, and authentication — enough to call it correctly. It omits error/failure behavior and does not spell out the `id` parameter, which keeps it short of complete.

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 only 33% — `slug` is documented, but `id` and `into` are bare integers in the schema. The description clarifies `into` as the target post id and implies `id` is the duplicate being merged, but it never explicitly says which parameter is the duplicate, leaving one required field to inference.

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 uses a specific verb ("combine a duplicate into another post") plus a clear scope ("Ideas and nominations"), and even shows the body shape `{ into: <post id> }`. An agent can distinguish this merge operation from moderation siblings like moderate_post or approve_all_posts without opening any 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?

It states a clear precondition and exclusion: "On a nomination only while suggestions are open," which tells the agent when the call will fail. It does not name a sibling alternative (e.g., moderate_post for hiding without merging), so it stops just 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.