send_direct_message

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

With no annotations, the description carries the full behavioral burden and discloses almost nothing. It does not mention that the send is irreversible (deletion requires a separate tool), that the recipient must have DMs open or share a server, or that rate limits/permission errors are likely.

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?

A single front-loaded sentence with no filler and no redundancy. It is exactly as long as the information it conveys.

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 write tool with no annotations and no output schema, the definition is thin: no return/confirmation behavior, no failure conditions, and no routing against the closely related DM and message tools. An agent can call it correctly but cannot anticipate what happens on success or failure.

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% and both required parameters (userId, message) are documented in the schema itself. The description adds no format, length, or content guidance beyond what the schema provides, so the 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+resource ('Send a direct private message') and scopes it to 'a specific Discord user', which implicitly separates it from the channel-oriented send_message. It stops short of explicitly naming that sibling or the read/edit DM siblings, so an agent must infer the distinction.

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?

No when-to-use guidance is given: nothing tells the agent to prefer this over send_message for channel posts, or over edit_direct_message / delete_direct_message for follow-up actions. The purpose implies the context, but no alternative or precondition is stated.

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