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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is well covered. The description adds valuable behavioral context by explaining the structure of the legs array and the absence of a campaign-level ruleset field, which helps the agent anticipate response shape and interpret results correctly.

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 two sentences with no filler. The core purpose is front-loaded, and the additional structural detail about the legs array earns its place by clarifying a non-obvious data shape. It is both concise and well-organized.

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 zero-parameter read-only list tool with an output schema and strong annotations, the description covers everything needed: what it returns, the key structural nuance, and how it relates to the sibling tool. There is no significant missing information.

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 tool has zero parameters and the schema is an empty object, so parameter semantics are trivially complete. Baseline 4 is appropriate since the description doesn't need to add parameter details and doesn't introduce any confusion.

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 precisely what the tool does: it lists campaigns where the calling user is a player, explicitly excluding the DM role. It also distinguishes the tool from play_list_my_campaigns by positioning it as the player-only view, making sibling differentiation clear.

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 context for when to use this tool: when you need campaigns where the user is a player, not a DM. It also names the sibling play_list_my_campaigns and recommends pairing them for a complete view, though it doesn't explicitly say when to choose one over the other beyond the player/DM distinction.

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