postSlackMessage

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It clarifies that the message is sent within the authenticated user's workspace, which is useful context. However, it does not disclose side effects (e.g., message appears as the user), permission requirements, or what the tool returns after sending, leaving some behavioral gaps.

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 a single sentence of 14 words that clearly and directly states the tool's behavior. There is no redundant or extraneous information, and it is appropriately front-loaded with the action.

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 required params, no output schema, no annotations), the description is nearly complete. It explains the action and the workspace context. It could mention return values or error handling, but for a straightforward send-message tool, this is sufficient for an agent to invoke 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?

The input schema already provides 100% description coverage for both parameters, including notes about the '#' prefix for channel and the message text. The description does not add significant semantic meaning beyond the schema, so the baseline 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 the specific verb 'Sends' with a clear object: 'a text message to a specified Slack channel.' This unambiguously states the tool's function and differentiates it from sibling tools like listSlackChannels (reading channels) and postTeamsMessage (posting to Microsoft Teams).

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 provides clear context for when to use the tool: when you need to send a message to a Slack channel. It does not explicitly mention when not to use it or alternatives, but the scope is obvious from the wording, so it earns a 4 rather than a 5.

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