send_direct_message

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

With no annotations provided, the description carries full responsibility for behavioral disclosure. It only states the action of sending a message, adding no information about side effects, authentication requirements, rate limits, or response behavior. For a mutation tool, this is a significant 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?

The description is compact and efficient, consisting of two concise sentences with no redundant information. It gets straight to the point.

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 tool's complexity (3 parameters, no annotations) and the existence of sibling tools like get_dm_history, the description is too brief. It lacks usage context, behavioral expectations, and any differentiation from alternatives. The presence of an output schema partially compensates for return value explanations, but overall completeness is insufficient.

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?

The description adds meaning to two of three parameters: it specifies that user_id is the recipient and explains reply_to as an optional message id. Although the text parameter is not described, its meaning is self-evident. Since schema coverage is 0%, this partial clarification still provides value.

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 tool's function: 'Send a direct message to a user id.' It uses a specific verb and resource, making the purpose clear. However, it does not explicitly distinguish this from sibling tools like get_dm_history, so it falls short of a 5.

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?

There is no guidance on when to use this tool versus alternatives. It does not mention any exclusions, prerequisites, or context for use. The description simply states the action without elaborating on appropriate scenarios.

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