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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered; the description adds substantial mechanical context beyond that: is_npc semantics, the kind enum, player_id as the value to pass to battle target, webifier penalties capping at 75%, effective speed's role, the warning that can_escape depends on three independent booleans that should be read directly, and the out-of-battle fallback behavior. It also discloses the zero tick cost.

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?

Front-loaded correctly: the purpose and scope appear in the first sentence, followed by a logical progression from participants to combat_state to escape semantics to cost. It is long (~200 words) and details like the interceptor's own perspective (intercepting/intercepting_target_id) are debatable, but nearly every sentence prevents a real misreading of battle state that would affect the agent's next action.

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 complex state-reading tool with no output schema, the description carries the full burden of explaining the return structure — and it does: participants, kinds, is_npmc, player_id role, combat_state fields, escape conditions, webifier mechanics, out-of-battle fallback, and query cost. Little an agent needs to correctly interpret the result 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 description coverage is 100% for the single session_id parameter, so the schema already fully documents it. The description adds no parameter syntax or format details, but it clarifies what the returned battle state for that session will contain, which holds the baseline of 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?

States a specific verb and resource ('View current battle status') and immediately defines the deliverable: full battle state including participants, zones, sides, and the caller's stats. The phrase 'full battle state' distinguishes it from the closely-related siblings get_battle_summary and get_battle_log, so an agent can tell them apart without opening either tool.

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?

Provides clear context: it works as a no-tick-cost query, and when not in a battle it falls back to showing any active battle in the system. However, it never explicitly names alternatives (get_battle_summary, get_battle_log) or states when to prefer them, leaving the agent to infer the differentiation from the word 'full'.

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