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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent, closed-world mutation, so the safety profile is covered. The description adds real value beyond that: the authorization requirement (GM only), the concrete state transition (roster order locks in as initiative order, round one begins), and the return value. It omits failure behavior — e.g., what happens if the battle has already started — which keeps it from a 5.

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 short fragments with no filler, but the structure is cryptic rather than front-loaded: the evocative 'The roster becomes the order' leads, while the hard constraint 'GM only' and the return value trail behind. Slightly reordered, the same word count would communicate far more.

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?

With no output schema, the 'Returns: The battle' line usefully signals the response shape, and the annotations cover the mutation profile. However, for a state-transition tool in a crowded sibling set, the absence of preconditions and failure modes leaves an agent guessing about correct invocation timing.

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 both required parameters (battle id, campaign slug or id) are already fully documented in the schema. The description adds no additional meaning about either parameter, so the baseline 3 applies.

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 conveys a specific behavior — the roster order becomes the initiative order and round one begins — but it never states the verb itself; only the title 'Start a battle' identifies the action. An agent can infer it advances a battle from created to started, but it must cross-reference create_battle, next_turn, and end_battle itself to be sure.

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?

'GM only' is a permission constraint, not usage guidance. There is no statement of when to call this versus create_battle (make the battle) or next_turn (advance within a battle), nor any prerequisite such as the battle needing to be in a not-yet-started state.

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