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

Adds meaningful context beyond annotations: it reads through the signed-in Slack Desktop app session, needs no token setup, and has a fallback behavior for older Slack Desktop versions. With readOnly/destructive annotations already present, this is solid additional behavioral context.

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 tight sentences, front-loaded with the core action and mechanism, followed by relevant operational caveats and the required prerequisite. No wasted text.

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?

Output schema exists, annotations cover safety, and the description covers session source, older-client fallback, and channel_id provenance. Complete enough for an agent to call it correctly, though it could explicitly mention pagination or search alternatives.

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 both parameters are already documented. The description reinforces that channel_id comes from slack_list_channels but adds little beyond the schema and does not elaborate on the limit parameter.

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 resource: reads recent messages from a Slack channel or DM. It differentiates from search by saying "recent messages," though it does not explicitly name slack_search_messages as the alternative.

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?

Provides a prerequisite that channel_id must come from slack_list_channels, but gives no explicit guidance on when to use this versus slack_search_messages or other message-reading siblings.

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