send_direct_message

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

Annotations already indicate readOnlyHint=false (write operation) and openWorldHint=true (potential side effects). The description adds the basic action but does not disclose additional behavioral traits like rate limits, auth requirements, or DM-specific rules (e.g., needing an open conversation). Given annotations, a 3 is adequate.

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, trimmed sentence of 7 words with no fluff. It front-loads the verb and resource, achieving maximum conciseness.

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 3 parameters, no output schema, and likely complex behavior (Twitter DMs), the description is insufficient. It omits context such as rate limits, recipient constraints, or how it interacts with conversations, making it incomplete.

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 no meaning beyond the input schema. The schema itself has 67% coverage (text parameter lacks description). The description does not compensate by explaining the text parameter or providing constraints, so it falls short.

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 uses a specific verb 'Send' and resource 'direct messages', clearly indicating the action. Among siblings like list_direct_messages and get_direct_message_conversation, it distinguishes itself as a write operation.

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, nor does it mention prerequisites (e.g., following the recipient) or exclusions. No context about when not to use it.

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