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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds genuinely new behavioral context: the authorization model (participant, public campaign viewer, or Admin Mode admin) and the default ordering and response shape, which an agent cannot derive from the 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?

Three compact sentences, front-loaded with the purpose, then access, then defaults. Minor redundancy in restating the `detail` parameter that the schema already explains, but no wasted sentences.

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?

An output schema exists, so return values need no explanation, and the description covers authorization and default response shape. It omits pagination semantics (limit is described as a cap with no mention of how to page past 200), which is a small gap for a list endpoint.

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 100%, so the schema already documents sort, limit, detail, and campaignId in detail. The description only restates the `detail: 'full'` option and the default ordering, adding no syntax, format, or constraint information beyond the schema — baseline 3.

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 and resource with scope: 'List sessions belonging to one campaign.' That scoping implicitly separates it from play_list_my_sessions and play_list_session_moves, but it never names or contrasts those siblings explicitly, so an agent must infer the routing.

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 gives a clear access condition ('Readable by anyone who may view the campaign...') and states defaults, which implies when the call will succeed. However, there is no explicit when-to-use guidance versus alternatives like play_get_session or play_list_my_sessions, and no exclusions.

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