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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=false, which covers the safety profile. The description adds the genuine lifecycle context that sessions are started, kept alive via heartbeat, and ended, which explains the non-idempotent flag. It still says nothing about what heartbeat returns, session timeouts, or the behavior of now_playing/library/set_wishlist.

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?

The single sentence is tightly written and front-loaded with action verbs, with no filler. Its brevity is achieved through under-specification rather than efficiency, leaving the majority of the enum unexplained.

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 multiplexed tool with six distinct actions, a nested untyped params object, no output schema, and no schema descriptions, the description is far from complete. An agent cannot determine what now_playing, library, or set_wishlist do, nor what to pass in params, without guessing.

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 0% and parameters are two, including a nested free-form 'params' object with no documented shape at all. The description explains only three of six action enum values and gives no information about what 'params' should contain for any action. With low coverage, the description should compensate but does not.

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 names a specific resource (game play sessions) and three verbs (start, keep alive, end), so the general purpose is graspable. However, the schema's action enum also includes now_playing, library, and set_wishlist, which the description never mentions, and there is no differentiation from siblings such as arcade_score. The stated purpose therefore covers only half of what the tool actually does.

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?

There is no guidance on when to call this versus arcade_score or any other sibling, and no explanation of the sequencing rules between start, heartbeat, and end. An agent must infer usage entirely from the one-line summary, which gives no context, prerequisites, or exclusions.

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