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

Annotations only declare readOnly and idempotent; the description adds substantial behavior: cloaked players are hidden, no scanning required, creature listing caps at 30 with creature_count holding the true total, player list caps at 50 with offline_collapsed above 10, and faction/prize fields that enable immediate action.

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 with the purpose and dense with useful detail, but the opening sentence is essentially restated inside the parenthetical ('Shows visible players... at your location without scanning'), which is mild redundancy. Overall still efficient for the amount of behavioral context packed in.

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 description carries the full burden of explaining return values, and it does so thoroughly: field names (actor_id, prize_id, creature_count, offline_collapsed, faction_name, livery colors) and list ordering semantics. Nothing needed to invoke or interpret the call 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?

Only one parameter (session_id) and schema description coverage is 100%, so the schema fully documents it. The description adds nothing about the parameter beyond what the schema states, which is the expected baseline for this situation.

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 opens with a specific verb and a precise enumeration of the resource (visible players, NPCs, creatures, intact prizes at your current POI). It proactively distinguishes itself from siblings like scan, get_system, and subscribe_observation, so an agent can route without opening schemas.

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 explicit when-to-use and when-not: sensors cover only this POI, and for other POIs the agent should use get_system (ship_count) or scan with a POI ID, both requiring a ship scanner. It also names 'scan' as the alternative for detailed info on a specific actor.

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