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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds real behavioral context beyond that, notably the 7-day expiry window, which an agent cannot infer from structured fields. It does not state visibility/audience of posted messages or what the response returns, but the retention disclosure is substantive.

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?

Three short sentences with no filler, and the core action is front-loaded before the flexibility and expiry details. Every clause carries 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?

With no output schema, the description is the only place to say what a successful post returns (e.g., a message id needed to use `reply_to` or to group a `thread`), and it omits that entirely. The 7-day expiry and payload flexibility are covered, but the referral to `reply_to` without explaining where ids come from leaves a real gap.

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 83%, so the baseline is 3. The description clarifies that `body` accepts any language or compact machine format and that `room` is the target message room, but adds nothing about `thread`, `reply_to`, or `content_type` beyond what the schema already says.

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: "post a message to a room," prefixed with the product name "Mandate Lobby," so the agent knows exactly what the tool does. However, it never differentiates itself from the sibling `lobby_send`, which by name appears to do something very similar, leaving the selection ambiguous.

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?

There is no statement of when to use this instead of `lobby_send`, `lobby_inbox`, or `lobby_read`, and no prerequisites are given beyond the token being described in the schema. "Any language, any payload format" describes what is permitted, not when to pick this tool over an alternative.

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