react

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

No annotations are provided, so the description carries the behavioral disclosure burden. It usefully reveals that an empty emoji removes the reaction, which is a non-obvious behavior. It does not cover permissions or additional side effects, but the most important behavioral edge case is documented.

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 extremely concise: two short sentences with no filler. The core action and the non-obvious empty-emoji behavior are both front-loaded, so every sentence earns its place.

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?

The tool is simple and has an output schema, so not documenting return values is acceptable. However, with no annotations, the description should at least hint at the purpose of the optional instance parameter and the behavior when emoji is omitted entirely. The current text is minimally adequate but leaves some call-time uncertainty.

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%, so the description must compensate for parameter meaning. It only clarifies the emoji behavior and leaves chat, message_id, and especially instance semantically under-specified. The required parameters are only explained by their titles.

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+resource: 'Reage a uma mensagem' (react to a message). It does not explicitly differentiate from siblings, but no sibling appears to duplicate the reaction functionality directly.

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 intended use is implied by the description, but there is no explicit guidance on when not to use this tool or how it compares to alternatives like send_text or send_media. It gives a clear context but no exclusions or alternative routing.

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