mattermost_create_post

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

The annotations already declare readOnlyHint=false, idempotentHint=false and openWorldHint=true, so the description is not on the hook for the safety profile. It still adds real value beyond them: the requirement for user authorization and the instruction not to blindly resend on timeout — concrete guidance that complements the non-idempotent hint. No mention of what a successful post returns or whether edits/deletes are possible.

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?

It is a single compact sentence with the action front-loaded and the constraints appended, so no reading time is wasted. Slight redundancy with the schema's message description is the only inefficiency.

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 two-parameter write tool whose annotations cover the safety profile, the description supplies the missing operational context (auth requirement, retry caution, content constraints). The remaining gap is target resolution — nothing explains the channelId or the boundary against reply_to_thread — but this is a minor omission rather than a blocking one.

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 50%: the 'message' field is already thoroughly documented in the schema, and the description's TL;DR/5-line/50-character rules largely restate it. The 'channelId' parameter carries only a regex pattern with no explanation anywhere, and the description does not clarify that it identifies the target channel or how to obtain it.

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 states a clear verb and resource ('發送訊息' / send a message) and identifies the acting identity ('以目前登入者身分'), which the tool name alone does not. It stops short of distinguishing this tool from its closest sibling, mattermost_reply_to_thread, so an agent must infer that this creates a top-level post rather than a threaded reply.

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?

It implies when the tool applies by describing prerequisites ('須有使用者授權') and a retry rule ('逾時不得直接重送'), and the formatting mandate narrows acceptable input. However, there is no explicit statement of when to prefer mattermost_reply_to_thread or mattermost_get_channel/channel-lookup first, leaving the main selection decision to inference.

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