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

Annotations only signal non-readOnly, non-idempotent, non-destructive behavior. The description adds substantial context: the two-way write to `imagineAdventures[]`, the backing of the session Adventure tag, caller permission requirements, and the 400 duplicate-link error. This far exceeds what annotations alone convey.

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?

Every sentence earns its place: the core mutation, the mirror side effect, auth constraints, the duplicate error, and the prerequisite lookup. The description is dense but well-ordered, front-loading the primary action and then layering important caveats.

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?

The description covers the operation's side effects, permissions, failure mode, and prerequisite step. Since an output schema exists, return-value documentation is not the description's burden. Nothing critical is missing for an agent to select and invoke this tool correctly.

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%, so the schema already documents both `id` and `campaignId` with meaningful descriptions. The main description adds operational context around the parameters but does not need to compensate for missing schema detail, keeping this at the baseline.

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 ('Add') and a precise resource ('a play campaign to an adventure's `playCampaignIds[]`'), making the operation concrete. The two-way mirror behavior further distinguishes it from related sibling tools like `imagine_unlink_adventure_from_campaign` and `imagine_link_world_to_campaign`.

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?

The description gives clear preconditions: confirm the link does not already exist, be ready for a 400, and locate the campaign id via `play_list_my_campaigns`. It does not explicitly name alternative tools like the unlink sibling, but the usage context is otherwise strong enough to guide an agent.

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