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

Annotations are minimal (readOnlyHint=false, destructiveHint=false, etc.), so the description carries the burden. It discloses that messages are heard by humans, that the message goes to the group or room-wide, and that roomWide overrides the default in a conversation. It adds behavioral context beyond the schema without contradicting annotations.

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 only three sentences, front-loaded with the core purpose ('Say something') followed by essential routing details and parameter usage. There is no fluff; every sentence earns its place and is well-structured.

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 simple say tool with 4 parameters and no output schema, the description is quite complete. It explains the routing logic, the roomWide flag, and the emote kind. It could benefit from a note on response behavior, but that is not critical given the simplicity. Overall, an agent has sufficient context to use 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 baseline is 3. The description adds valuable semantics for 'kind' (emote example) and clarifies the interaction between room, conversation, and roomWide through the routing explanation. This goes beyond the dry schema descriptions and helps an agent use the parameters correctly.

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 clearly states the verb 'say' and the resource (a message in a room or conversation), and explains the routing behavior based on whether the user is in a conversation. It distinguishes from sibling tools like read_conversation or join_conversation by focusing on sending a message, but does not explicitly name alternatives.

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?

The description gives clear context: in a conversation it goes to that group, otherwise it's room-wide bar chatter. It also explains the roomWide parameter for addressing the whole room while in a conversation, and shows when to use kind 'emote'. It does not explicitly state when not to use the tool, but the guidance is sufficient for an agent to decide.

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