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

Annotations only carry destructiveHint=false and a title, yet the description discloses non-obvious behavior: the bot is automatically in a created channel and can post immediately, the DM path deliberately uses the connecting person's token to avoid creating a DM with the app, channel creation is workspace-visible, required scopes differ per path, and old workspaces return a reconnect hint. This is exactly the extra context annotations cannot provide.

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?

Front-loaded with the two paths and tight, but the heavy em-dash parentheticals make it dense to parse and the multi-clause sentences are longer than necessary. Every clause still carries information, so no real waste — just lower readability than a 5.

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 4-param, no-output-schema tool, it covers the branching logic, permission requirements, side effects, and the return value (channel id) needed for the next call. Nothing an agent needs to invoke it correctly is missing.

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 coverage is 100%, so baseline is 3, but the description adds genuine semantics beyond the schema: the mutual-exclusivity rule between channel_name and user_ids, the 1-vs-2-8 id boundary, and the meaning shift of user_ids (invitees vs DM participants). It does not, however, cover the account parameter's multi-workspace condition.

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?

States a specific verb and two distinct resources (channel creation vs DM/group-DM opening) and immediately disambiguates them by parameter shape. An agent can tell this apart from siblings like manage_slack_channel or send_message without opening the schema.

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?

Explicit branching rule: pass channel_name for a channel (with optional is_private/user_ids), pass ONLY user_ids for a DM (1 id) or group DM (2-8 ids). It names the destination sibling ('the channel id to use with send_message') and adds a confirmation prerequisite for the workspace-visible case.

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