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

With no annotations, the description carries the full burden and does so well: it discloses that no new message is created, that the same emoji again removes the reaction (toggle/idempotency behavior), that ✅ on a message to you also marks it resolved (a side effect), and that all participants see the reaction (visibility). These are non-obvious behavioral traits an agent could not infer.

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 core action is front-loaded and the whole definition is compact with no filler sentences. The nested parenthetical about ✅ being resolvable and the toggle note add density, but each clause carries distinct, useful 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?

For a 2-parameter tool with no output schema and no annotations, the description supplies the missing behavioral context: what the reaction does, how to undo it, the resolution side effect, and who sees it. Only minor gaps remain (e.g., error behavior for an invalid message id), so it is largely complete.

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, but the description adds value the schema lacks: the meaning conventions tied to specific emoji values and the fact that re-sending the same emoji toggles it off. It clarifies the semantic role of 'id' as the target message, though it does not add format details beyond the schema's example.

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 ('Reage com um emoji a uma mensagem') and explicitly distinguishes itself from sending a new message ('sem mandar mensagem nova'), which cleanly separates it from the sibling aicq_send. An agent can identify what this does and how it differs from neighbors without opening the 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?

The description gives semantic conventions for when to use which emoji (👍 entendi, 👀 vou ver, ✅ feito), which is real usage guidance, and the 'sem mandar mensagem nova' clause implicitly tells the agent when to prefer reaction over sending. It never states explicit exclusions or names an alternative tool, so it falls short of a 5.

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