send_private_message

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

With no annotations provided, the description carries the full burden of disclosing side effects, permission requirements, or send constraints. It only states the action and the recipients format; it does not mention authentication needs, whether this is a write/mutation operation, rate limits, or any expected outcome. This is a significant gap for a communication-sending tool.

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 brief and front-loaded with the primary purpose. It does not waste words, and the recipients clarification is useful, though it duplicates the schema. It is appropriately concise but could have used the available space to add behavioral or usage context.

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 tool with three required parameters, no annotations, and no output schema, this description is under-specified. It omits when to use it, how it relates to send_chat_message, what a successful send returns, and any prerequisites. An agent has only the bare action and a parameter hint, which is not enough for confident invocation in a real workflow.

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 67%, and the description only repeats the recipients meaning already present in the schema. It adds no meaning for 'title' or 'raw' beyond their types, and the Markdown body description is already in the schema. The baseline of 3 is appropriate because the schema does most of the work, but the description gives no extra value for parameters.

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 phrase 'Send a private message' states a specific verb and resource, clearly distinguishing the core action from topic creation or chat messaging at a basic level. It doesn't explicitly differentiate from sibling tools like send_chat_message, but the action is unambiguous enough for an agent to know what the tool does.

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 provides no guidance on when to use this tool versus alternatives such as send_chat_message or create_topic. It gives no context about audience, privacy semantics, or situations where a private message would be appropriate, leaving the agent to infer usage entirely.

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