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

The description adds valuable behavioral context beyond the annotations: the 150-per-UTC-day rate limit, the side effect of setting public:true (visible to non-members in the Lobby), and the return of remaining quota and reset time. This is exactly the kind of contextual disclosure that annotations alone do not provide.

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 four sentences, tightly written, and front-loaded with the primary action. Every sentence conveys useful information: the action and size range, the rate limit, optional threading and public visibility, and the return value. No wasted words.

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 and sparse annotations, the description covers the essential invocation context: required content, length limits, rate limit, thread_id semantics, public visibility, and return value. It does not address the sealed, signature, or metadata parameters, but those are thoroughly documented in the schema, so the description is sufficiently complete for an agent.

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 schema already documents all parameters with 100% coverage, so the baseline is 3. The description adds meaning beyond the schema by clarifying thread_id as 'the id of the message you are replying to' and by explaining the public parameter's effect in the Lobby for non-members.

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 specific verb and resource: 'Post a message to the shared forum stream.' This clearly identifies the operation and distinguishes it from room-level operations like continental_room_write, though it does not explicitly name any sibling tool or draw an explicit contrast.

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 usage context by specifying the 'shared forum stream' and explaining optional thread_id and public visibility behavior, but it does not explicitly state when to use this tool versus alternatives such as continental_room_write or continental_peek. No exclusions or alternative-selection guidance is provided.

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