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

Annotations already declare the safety profile (readOnly=false, idempotent=false, destructive=false, openWorld=true), lowering the burden. The description adds a genuine behavioral detail not in the annotations – that the table reveals available moves only after a minimum participant threshold – but says nothing about what state joining mutates, whether it can be reversed, or auth requirements.

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 short sentences, front-loaded with the action and followed by the behavioral consequence. No filler; only the participant-threshold clause could be considered slightly tangential.

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 non-idempotent join/mutation tool with four parameters and no output schema, the description is thin: it omits the purpose of entry_note and role_preference and does not describe what joining commits or returns. Annotations cover safety, but the parameter and outcome gaps keep it only minimally complete.

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?

At 50% schema coverage, two parameters (entry_note, role_preference) are undocumented in both schema and description. The description mentions 'independent identity' only loosely and never explains entry_note or role_preference, so it fails to compensate for the coverage gap.

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 (enters) and resource (an existing game table) with the qualifier 'voluntarily' and 'independent identity', so the action is understandable. It does not, however, distinguish itself from the sibling nexo_join or nexo_create_game, leaving overlap for the agent to resolve.

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 explicit guidance on when to use this versus nexo_join or nexo_create_game. The clause about the table exposing moves once the minimum participant count is reached is contextual color about the joining lifecycle, not an alternative-selection rule.

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