send_message

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 only states the action ('Post') but does not mention side effects, response format, authentication requirements, or any error conditions. This is a significant gap 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?

The description is a single, direct sentence with zero fluff or redundancy. It is appropriately concise and front-loaded, though it sacrifices context for brevity.

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?

With two well-documented parameters and an output schema present, the description is minimally viable. However, it lacks usage guidance and behavioral context (e.g., when to use this over siblings, what the response contains). The complexity is low, so the missing details represent clear but not fatal gaps.

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 comprehensive descriptions for both parameters (text and blocks) with 100% coverage. The description adds no additional parameter semantics, so it does not exceed the baseline established for high schema coverage.

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 ('Post') and resource ('Slack message'), and mentions the method ('via Incoming Webhook'). It clearly conveys the tool's primary function, but does not differentiate it from sibling tools like send_payload or send_markdown.

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 no guidance on when to use this tool versus alternatives. With sibling tools present, the lack of any usage context or exclusions leaves the agent to guess based solely on the tool name.

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