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

Annotations already declare destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds only that the message is internal and thread-scoped; it does not say whether the thread must already exist, whether this creates a thread, or what happens on failure — useful context that is missing for a write operation.

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?

One short, front-loaded sentence with no filler. It is efficiently written, though its brevity is part of why usage and threading behavior go unexplained.

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 simple three-parameter send tool with a fully described schema and no output schema, the definition is minimally adequate. It omits the routing guidance against sibling send tools and the thread preconditions, which an agent needs to choose and call it correctly.

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 coverage is 100%, with body, thread_id, and purpose each documented in the schema itself. The description adds no meaning beyond that (e.g., whether thread_id can be created on the fly), so the baseline of 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?

The description states a specific verb and resource ("Sends an internal direct message") and scopes it to "a SautiDesk agent thread," which separates it from the external-channel senders. It stops short of naming how it differs from close siblings like desk_send_message or desk_send_nudge, so the differentiation is only implied.

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?

"internal" hints that this is for agent-to-agent messaging rather than customer channels, but there is no explicit when-to-use or when-not-to-use statement. With siblings such as desk_send_message, desk_send_nudge, and desk_send_sms in the same family, the agent is left to infer which send tool applies.

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