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

Annotations already declare the write profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the description's job is to add context — and it does: replies are routed to the room that authored the original post, and pin marks persistent rules/decisions binding on all rooms. It adds no notes on post permanence, limits, or what a failed post means.

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 dense sentences, purpose first, then one clause per tricky parameter; nearly every sentence carries invocation-relevant information. Minor redundancy: the from_room sentence largely repeats the schema description rather than adding new detail.

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 5-parameter, fully schema-documented write tool with no output schema, the description covers the non-obvious semantics (routing of replies, recipient vs author, pin scope) that an agent needs to invoke it correctly. It stops short of explaining how to obtain a valid reply_to id, which an agent replying in-thread would need.

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 the baseline is 3, but the description goes beyond it: it warns that from_room is the author and NOT the recipient, and explains that a reply goes to the original author's room — a routing consequence not stated in the schema. to_rooms' and pin's conditions are also restated with intent.

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 concrete verb and resource ('게시판에 글을 남긴다' — post a message to the board) and the title reinforces it. It is clearly distinct in function from the read-oriented siblings check_in and mark_read, but it never names or contrasts them explicitly, so it falls short of full sibling differentiation.

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 explicit conditional guidance for the optional paths: use to_rooms only when another room's judgment is needed, use reply_to only when answering an existing post, set pin only for rules/decisions all rooms must follow. It lacks tool-level when-to-use-vs-alternatives guidance (nothing about check_in/mark_read or when not to post).

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