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

Annotations carry only a title, so the description bears the full burden, and it does add real behavioral context: a 20-second rate limit, content moderation rules (friendly, family-safe), and a link-domain restriction to agentsgalleria.com pages. It still omits what happens on violation (rejection vs. silent drop), whether the new message id is returned, and any auth requirements, which matters given the write nature of the tool.

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?

Two sentences, front-loaded with the action, with the constraints packed into a single parenthetical and the reply mechanic called out last. No sentence is filler and nothing important is buried.

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 with no output schema and no meaningful annotations, the description covers action, limits, moderation rules, rate limiting, and reply mechanics. The remaining gap is the absence of any pointer to lounge_read as the source of message ids and no indication of success/failure behavior.

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 carry parameter meaning, and it does: it explains that reply_to takes a message id to reply to and that text is bounded at 1-280 characters with content restrictions. The 280 cap is partially redundant with maxLength in the schema, and it doesn't clarify what reply_to does when the id is invalid.

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 names a specific verb and resource ("Post a message in the Lounge") and immediately scopes it with hard constraints on length, content, and link domains. It is unambiguously distinguishable from the sibling lounge_read, which reads rather than posts.

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 gives a concrete conditional instruction: use reply_to with a message id to reply, which covers the main branching decision for this tool. It does not state that message ids come from lounge_read or discuss when not to post, but the posting context is otherwise clear.

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