send_dm

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

With no annotations provided, the description fully discloses that this is a write operation and explains the critical behavioral constraint of the 24-hour window, including the risk of rate limits on failure.

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 concise with two short sentences and a paragraph, all front-loaded with the core action. Every sentence adds value with no redundancy or fluff.

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 complexity of the DM tool (write operation with a time constraint), the description covers essential behavioral context. It does not detail error codes or exact rate limit behavior, but it is sufficient for an agent to understand key constraints. The presence of an output schema reduces the need for return value descriptions.

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?

While schema coverage is 100% and baseline is 3, the description adds context beyond the schema by explaining that the recipient_igsid comes from get_messages and by relating the messaging window to the parameters. This provides additional meaning.

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 'Send a DM reply to a user,' which is a specific verb-resource combination. It distinguishes itself from sibling tools like 'send_human_agent_dm' by focusing on direct DM replies.

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 explicitly mentions the 24-hour messaging window and warns that cold DMs will fail, providing clear guidance on when to use the tool and when not to. It also notes that message tags are not supported, further clarifying limitations.

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