im_thread_messages

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

With no annotations provided, the description carries the full burden. It discloses two critical behaviors: the operation is READ-ONLY and it uses fallback scanning when im.v2 is unavailable. This gives the agent a clear safety profile and an understanding of the underlying behavior, though it omits details like authentication or rate limits.

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, front-loaded sentence that immediately communicates the READ-ONLY nature and the core function. It is concise with no filler, and every phrase adds value.

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?

The tool has six parameters and no output schema, yet the description does not mention return format, pagination behavior, or how the limit and scan_pages parameters affect results. The fallback scanning note adds useful context, but overall the description is sparse for a tool of this complexity, leaving some 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 100% description coverage for all six parameters, so the baseline is 3. The description itself adds no additional parameter semantics beyond the schema, not even connecting the fallback behavior to scan_pages or thread_dialog_id.

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 a specific action ('read existing thread (comments) of a channel message') with an explicit READ-ONLY marker. This distinguishes it from write/reply tools like im_thread_reply and im_chat_messages, making the purpose unambiguous.

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 the tool is for reading existing threads but does not explicitly state when to prefer it over similar read tools like im_message_comments or how to handle fallback scenarios. No exclusions or alternatives are named, so usage context 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.