send_ephemeral

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

With no annotations provided, the description carries the behavioral disclosure burden. It accurately conveys ephemerality and the visibility scope, both of which are meaningful behavioral traits. It does not elaborate on error conditions or whether the message appears in history, but the core ephemeral behavior is clearly stated.

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 one sentence with no filler. The core behavior is stated first, and every word contributes meaning. It is appropriately sized for a simple tool.

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 three-parameter tool with fully documented schema properties, the description plus schema is sufficient to understand how to invoke it. The main omission is usage guidance versus siblings, but that is already penalized under usage guidelines. No output schema exists, so return-value documentation is not required.

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%, so the schema already explains text, user, and channel. The description adds the 'visible only to a specific user' nuance, which reinforces the user parameter but provides little beyond the schema. A baseline score of 3 is appropriate.

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 clear verb ('Send') with a specific resource ('an ephemeral message') and states the audience constraint ('visible only to a specific user'). This clearly differentiates it from regular message-sending sibling tools like send_message.

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 gives no explicit guidance on when to choose this tool over alternatives such as send_message or reply_in_thread. The context is evident from the name and description, but the tool does not state exclusions or conditions for its use.

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