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

Annotations already establish that this is a safe, read-only, idempotent operation. The description adds useful behavioral context beyond those annotations: membership requirement, default compact summary shape, most-recently-updated ordering, and the `detail: 'full'` opt-in for the populated shape.

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?

Two sentences, no filler. The action and membership requirement are front-loaded, followed immediately by the most decision-relevant parameter behavior. Every sentence earns its place.

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 read-only listing tool with an output schema and full annotations, the description covers the essential operational context: campaign scope, membership precondition, and the shape/ordering defaults. Nothing critical is missing for an agent to invoke this 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 carries the full parameter documentation. The description complements it by highlighting the practical choice between summary and full shapes and noting the default ordering, which reinforces the meaning of `sort` and `detail` without repeating schema details.

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 and resource ('List sessions') and clearly scopes the operation to one campaign. The title and description together unambiguously distinguish this from sibling list tools like play_list_my_sessions.

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 states the key prerequisite ('Caller must be a member of the campaign') and gives clear context on default behavior. It does not explicitly name alternatives or state when not to use it, but the intended use case is clear from the one-campaign scope.

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