list_channel_messages

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

With no annotations, the description carries the full burden and does so: it discloses ordering semantics ('threads with the latest activity first'), the absence of pagination ('there is no cursor for older ones'), and content exclusions ('System messages are excluded'). It also names fields returned and points inline image ids at download_attachment, which is well beyond a bare restatement.

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 purpose, then prerequisites, then behavioral caveats - a sensible order with no filler sentences. The middle return-fields sentence is dense and slightly sprawling, but each clause carries operational information.

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?

An output schema exists so return values need not be enumerated, yet the description still summarizes the shape usefully. Combined with the ordering, pagination and exclusion notes, nothing an agent needs to call this 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 description coverage is 0%, so the description must compensate, and it does for the key range constraint ('up to `limit` (1-200)') and for the provenance of team_id and channel_id via the discovery chain. It does not describe id formats or what happens if limit is omitted, leaving a small gap.

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 ('List recent top-level messages in a Teams channel') and immediately constrains scope with the word 'top-level'. It cleanly distinguishes itself from siblings like list_thread_replies and list_chat_messages, which an agent can tell apart without opening the schemas.

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 an explicit prerequisite chain ('Use list_teams -> list_channels to get team_id and channel_id') and an explicit exclusion with a routed alternative ('Replies are not included - read a thread with list_thread_replies'). Both when-to-use and when-not-to-use are covered.

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