slack_read_thread

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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the description's added value is real: it discloses the auth requirement for private channels and the pagination contract via next_cursor. It also explains how mentions are rendered and what user_names contains, which is behavioral detail an agent cannot get from annotations or schema.

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?

Four short sentences, front-loaded with the core action and pagination immediately after. The closing note about user_names and <@ID> mentioning drifts toward slack_send_message usage, but it is brief and still informs interpretation of this tool's output.

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 no output schema, the description carries the burden of explaining returns, and it does so for the parts an agent must handle: pagination cursor, mention rendering, and the user_names mapping. It does not describe the overall response shape (e.g., whether the parent message is included in the list), which is the main remaining gap.

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 75%, with limit left undescribed, so the schema does most of the work. The description still adds meaning beyond it by tying cursor to the next_cursor value returned from the previous page, which is the one non-obvious parameter interaction.

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 a parent message plus its thread replies. That scope ('thread replies') implicitly distinguishes it from slack_read_channel and slack_search_messages, but no sibling is named explicitly, so differentiation is inferred rather than stated.

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?

Gives one real prerequisite (a user token is needed for public/private channel threads), which is genuinely useful selection context. However, it never says when to choose this over slack_read_channel or slack_search_messages, so the usage guidance is implied rather than explicit.

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