slack_post

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

Annotations already indicate this is a non-read-only, non-idempotent, non-destructive operation. The description adds valuable context about the channel membership requirement and the expected error if the bot is not invited, going beyond the annotations.

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?

Three concise sentences, each earning its place: the action, the usage context, and a key prerequisite/error note. No redundant or filler content.

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 posting tool, the description covers purpose, usage timing, and a critical operational requirement. The output schema is present, so there is no need to describe return values, making the description complete.

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 does not discuss parameters, but the input schema comprehensively describes both 'text' (required) and 'channel' (optional). Since the schema carries the parameter semantics, the description does not need to repeat them; baseline 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 clearly states it posts a message to Slack via chat.postMessage, with a specific verb and resource. It also frames the use case (delivering a final report after email/calendar processing), which distinguishes it from the sibling Gmail/calendar tools.

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 says 'Use this to deliver the final report after processing emails and registering calendar events,' giving clear when-to-use context. It also mentions the prerequisite that the bot must be a member of the channel, which is important operational guidance.

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