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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds meaningful behavioral context: the 24-hour window, the 'visible' scope, and the explicit statement that message content and participant identities are not returned.

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 short sentences carry the complete definition: the first front-loads the action and result, and the second clarifies a critical limitation. There is no filler or restating of the tool name.

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 single-parameter read-only tool, the description covers the key return values, the time window, and a major limitation. There is no output schema, but the expected data points are enumerated clearly; only exact response formatting is left unspecified.

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%, and the description never states that the required `name` parameter identifies the room being queried. The parameter name is inferable from the tool name, but with no schema description and no explicit mapping in the tool description, the agent is left to guess.

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 opens with a specific verb ('Read') and identifies the resource and exact outputs: visible message and participant counts for the last 24 hours, plus last message time. It also explicitly excludes content and participant identities, which distinguishes it from siblings like read_messages.

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 final sentence ('No content or participant identities') implies this tool is for summary-level activity rather than content retrieval, and the 24-hour window suggests it is not for historical queries. However, it never explicitly names an alternative tool or states exactly when an agent should prefer this over read_messages or get_room.

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