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

Annotations already indicate this is not read-only and not idempotent, and the description adds useful behavioral nuance: passing hidden sets the state explicitly, while omitting it flips the current state. This clarifies the non-idempotent toggle behavior beyond the bare annotation flags.

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 front-loaded sentences convey the action, purpose, and the critical set-vs-toggle distinction with no wasted words. 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 simple three-parameter tool with no output schema, the description plus schema covers the required combatantId, optional hidden semantics, and combatId fallback described in the schema. It could add a note about the return value, but nothing essential is missing for correct invocation.

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 all three parameters are already documented in the schema. The description restates the hidden/toggle behavior rather than adding new parameter-level meaning, which matches the baseline for complete schema coverage.

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 the specific verb pair 'Set or toggle' with the clear resource 'a combatant's visibility to players', then grounds it with concrete use cases (hidden enemies, invisible creatures, surprise). No sibling tool covers this visibility behavior, so it is readily distinguishable from the combat sibling set.

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 operational context: use this to hide or reveal combatants to players, with examples of when that matters. It does not name explicit alternatives or exclusions, but there is no closely competing sibling tool for this action, so the context is sufficient.

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