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

Annotations only convey readOnly=false, idempotent=false, destructive=false. The description goes far beyond: it explains the side effect (mutating playCampaignIds[]), the derived effect on the campaign's imagineAdventures[] and session Adventure tag, and details error codes (403, 404, 400) with conditions. This fully discloses behavioral impact without contradicting annotations.

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 dense paragraph, but every sentence contributes: core action, side effects, access control, error codes, preconditions, and a pointer to a helper tool. It is front-loaded with the primary verb and object, and no sentence is redundant.

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 mutating link operation, the description covers all essential context: what, where, side effects, permissions, error handling, and input sourcing. With an output schema present (though not shown) and annotations covering safety, nothing an agent needs to invoke correctly is missing.

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 baseline is 3. The description adds value by explicitly stating where to get campaignId (from play_list_my_campaigns or play_list_participated_campaigns) and that id is a Mongo _id of the adventure. This enriches the schema's minimal descriptions, so a 4 is warranted.

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 clearly states the action: 'Add a play campaign to an adventure's playCampaignIds[]'. It names the specific resource, the exact array field being modified, and distinguishes itself from the sibling tools imagine_unlink_adventure_from_campaign and imagine_link_world_to_campaign by specifying the exact data model.

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 explicitly tells when to call it ('call this only when you've confirmed the link isn't already present'), provides error-handling guidance ('or be ready to handle the 400'), and directs the agent to use play_list_my_campaigns to find the campaign ID. It also states required permissions (owner/gamemaster + edit access on adventure).

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