create_channel_message

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

With no annotations, the description carries the full burden. It discloses the need for a specific permission, respects rate limits, and content length limitation. However, it does not describe the return value or side effects (e.g., whether it returns the created message). Still provides useful behavioral context beyond basic purpose.

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?

Very concise: two sentences plus a bullet of constraints. All information is relevant and front-loaded with the action. No filler or redundancy.

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 tool's simplicity (2 params, has output schema), the description covers purpose, permission, and constraints adequately. However, it omits any mention of the output (what the tool returns), which is relevant for an agent using it. The presence of an output schema is not leveraged in the description.

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 0%, so description must compensate. It only adds that content is limited to 2000 characters, but provides no explanation for channel_id or additional details for content (e.g., formatting, allowed characters). This adds minimal value beyond the parameter names.

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?

Explicitly states it sends a text message to a channel, with a clear verb and resource. Siblings are all read/list operations, so this is uniquely identified as the write operation for messages.

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?

Mentions required permission 'Send Messages' and constraints like rate limits and 2000 character limit. While it doesn't explicitly compare to siblings, the context makes it clear when to use this tool (to create a message) vs others (to read). A clear when-to-use is present.

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