slack_send_message

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

With no annotations present, the description carries the burden of behavior disclosure, and it does a solid job: 'AS YOU (not as a bot)' and 'appear exactly as if you typed it' communicate identity and user-visible effect. It does not mention side effects such as messages being immediately visible to others or being effectively irreversible through this tool, but the core behavioral nuance is captured.

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?

Two tight sentences deliver the essential information: identity ('as you'), behavior ('appear exactly as if typed'), and destination formats. Every clause earns its place, and the most important behavioral distinction is front-loaded.

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 three-parameter tool with 100% schema coverage and no output schema, the description is nearly complete: it identifies what to send, where, and how the send is attributed. The main gap is not clarifying thread vs. top-level message behavior relative to sibling tools, but that does not prevent a competent agent from calling this tool correctly for normal messages.

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 baseline is 3; the schema already documents channel and text. The description reinforces the channel formats ('#channel-name, @username (DM), or channel ID') but does not add new meaning beyond the schema, and the workspace parameter is not mentioned in the description at all.

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 the action ('Send a Slack message') and resource, and adds the important nuance that it sends as the user, not a bot. It also mentions supported destination formats (#channel, @user, channel ID). It does not explicitly distinguish this from sending into a thread, which slack_reply_thread covers, so it stops short of full sibling differentiation.

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 implies when to use it: whenever a Slack message needs to be sent, with guidance on where (channel, DM, or channel ID). However, it never explicitly says when not to use it or points to alternatives such as slack_reply_thread for thread replies, leaving routing to sibling tools implicit rather than explicit.

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