Send message into in-game or lobby chat

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

Annotations already declare the write/destructive/open-world profile, so the bar is lower. The description adds genuinely useful context beyond them: auto-resolution of the active team/lobby chat when conversationId is omitted, and the required write-allowlist endpoint ('POST /lol-chat/v1/conversations/*/messages'). It does not address the destructiveHint flag (e.g., that the message is public and cannot be recalled), leaving one gap.

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 core action, followed by usage, alternative, behavior, and auth in a logical order. Slightly redundant: 'Sends a text chat message...' and the later 'Behavior: Sends a chat message to client conversations' repeat the same premise, costing a bit of tightness.

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 two-parameter action tool with no output schema, the description covers everything needed: what it does, when to use it, the sibling alternative, default-resolution behavior, and the authorization requirement. An agent has sufficient information to call it correctly.

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 the schema already documents both message and conversationId thoroughly. The description's note that conversationId omission auto-resolves the active chat largely restates the schema's own wording; it adds no further format, length, or edge-case detail. Baseline 3 applies.

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 (sends) and resource (text chat message) plus the exact scope it targets: champion select, lobby, custom game conversation, or a specific conversation ID. It explicitly distinguishes itself from the sibling lol_chat_status, so an agent can route correctly without opening either schema.

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?

Explicitly says when to use it (communicating team plans, role preferences, or greetings during lobby or draft phases) and names the alternative (lol_chat_status) with the condition that selects it (availability/custom status updates). Both the positive trigger and the exclusion are present.

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