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

The description goes well beyond annotations (which only declare readOnlyHint and destructiveHint) by detailing error codes (401, 403, 404, 502), auth restrictions (user/B2B, not app-token), and the pagination cursor behavior (nextBefore for older pages). It also mentions the mamUnavailable flag for deployments without archives. This is a high level of behavioral disclosure.

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 a single dense paragraph, but it is well-organized: purpose first, then output format, then identification, then auth, then errors. Every sentence adds value. It could be split into bullet points for readability, but it's not overly long and stays focused.

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 read-only tool with no output schema, the description covers all essential aspects: endpoint, response fields, pagination, room identification, auth modes, and error cases. Nothing an agent needs to successfully call this tool is missing.

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. The description adds little beyond the schema: it restates the roomJid format, the optional appId, and the either/or requirement. It does add the output fields and cursor, but that's not parameter-specific. Since the schema already explains parameters well, and the description merely echoes that info, a 3 is appropriate.

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 clear verb ('Read'), resource ('archived messages of a chat room'), and explicitly gives the endpoint path. It distinguishes from sibling tools by focusing on reading history, unlike search or send. No ambiguity about what this tool does.

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 provides essential usage context: how to identify the room (via roomJid or chatId+app), supported auth modes, and what the response contains. It does not explicitly contrast with sibling tools (e.g., ethora-messages-search-v2), but the purpose is clear enough that an agent would not confuse it with sending or searching. A slight deduction for not stating when NOT to use this tool.

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