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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description adds real behavioral depth: pagination order ('newest last'), the nextBefore cursor, accepted vs rejected auth modes ('app-token mode is not accepted'), and specific error semantics including MAM_READ_FAILED / mamUnavailable. This far exceeds what the annotations convey.

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?

Front-loads the core purpose before endpoint, return shape, prerequisites, auth, and errors. It is dense but nearly every clause carries distinct, useful information; only the raw endpoint path borders on redundant detail.

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 compensates by describing the return shape (from, nick, body, ts in ms, nextBefore cursor) and enumerating auth and error cases. An agent has everything needed to invoke and interpret the result correctly.

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 100%, so all five parameters (including roomJid format and the before cursor) are already documented in the schema. The description mostly restates the roomJid/chatId relationship and confirms appId is optional rather than adding new syntax or constraints beyond the schema, warranting the baseline 3.

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+resource ('Read the archived messages of a chat room') and even supplies the underlying endpoint. It is clearly distinguishable from the sibling ethora-message-send (write) without opening any schema.

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?

Gives the prerequisite ('a room in the selected app' via ethora-chat-create) and names ethora-app-select for app selection, which routes the agent well. It does not explicitly compare against an alternative read tool (none exists), so it stops just short of full when/when-not guidance.

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