send_dm

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

Annotations already indicate it's not read-only (write) and not destructive, so the description adds the key behavioral detail that the DM room is created automatically if it doesn't exist. This goes beyond 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 a single sentence with no waste. However, it could include parameter details without significantly increasing length. It is efficient but not perfectly structured for maximum utility.

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?

Given the presence of an output schema and annotations, the description covers the essential behavior but lacks parameter details. For a simple tool, it is minimally complete but leaves ambiguity about parameter inputs.

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?

With 0% schema description coverage, the tool description must compensate but provides no explanation for the two parameters (username, text). The agent cannot infer meaning constraints (e.g., user existence, text length or formatting) from the description alone.

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 action 'Send a direct message to a user', which is a specific verb-resource combination. It distinguishes from siblings like send_message (channel) and reply_to_thread by focusing on DM, and adds the nuance of auto-creating the room.

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 hints at when to use by noting it creates the DM room if needed, implying it's the primary DM tool. However, it does not explicitly mention when to avoid it (e.g., for existing channels or threads) or compare with alternatives like send_message.

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