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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds one genuinely useful behavioral note — no WebSocket, i.e. a non-live fetch — but says nothing about how many messages are returned, ordering, pagination, or rate limits. With annotations carrying the safety burden, a 3 is appropriate.

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?

A single short sentence that front-loads the resource and action with no filler. It is efficient, though the terse parenthetical is the only qualifier and adds little structure.

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 simple one-parameter read tool whose annotations cover the safety profile, the essentials are present. However, with no output schema, the description does not indicate what the returned messages look like or their count/ordering, and it offers no usage routing — leaving notable gaps for an agent deciding between chat_history, get_history, and chat_send.

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?

There is a single parameter (channel_id) with 100% schema description coverage, so the schema already documents the required 'ID do canal no catálogo'. The description adds no format, source, or lookup details beyond that, matching the baseline 3 for a fully documented single parameter.

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 resource ('últimas mensagens da sala de um canal') and a retrieval action, so an agent can tell it fetches recent chat messages for a channel. It does not explicitly contrast itself with near siblings like get_history or chat_send, which keeps it short of a 5.

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 when-to-use guidance and no reference to alternatives such as chat_send (posting messages), get_history (other history), or clear_history. The only hint is the parenthetical '(sem WebSocket)', which implies a polling/HTTP fetch but without saying when that is preferable.

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