Join match

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

With no annotations provided, the description carries the full burden. It discloses the key side effect ('Launches a browser and connects to the live game') and the optional random matchmaking path. However, it does not mention what happens on invalid codes, wait times, or how the agent learns whether the join succeeded.

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 description is two sentences with zero filler. The core action is front-loaded, and the optional-code behavior is stated immediately after without unnecessary detail.

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 low-complexity tool with one optional parameter and no output schema, the description covers the essential context: what the tool does, how it behaves, and the optional mode. It would be slightly stronger if it noted the post-join outcome, but the core usage is adequately 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?

Schema coverage is 100% and the schema already describes the 'code' parameter. The description adds meaningful behavioral context by explaining that omitting the code triggers random matchmaking, which goes beyond the schema's static parameter description.

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 states a specific verb ('join'), a specific resource (a friendly 1v1 match as the second player), and the mechanism (using a match code). It clearly distinguishes this tool from the sibling game-control tools by naming the match-joining action.

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 explicitly tells the agent when to use the tool ('using the match code the human shares with you') and provides the alternative behavior when no code is available ('Omit the code to enter random matchmaking instead'). This is precise and leaves no ambiguity.

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