react

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

No annotations are provided, so the description carries the full burden. It does disclose an important behavior — empty emoji removes your existing reaction — and the default behavior of 'to' (sole subscribed target), but stays silent on permission requirements, error cases, and whether reactions are idempotent.

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 action in one sentence, then a compact Args list. Every line carries information; only the arg labels restate parameter names, which is acceptable in this format.

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 3-parameter mutation tool with an output schema available, the description covers all parameters and the key behavioral nuance (reaction removal). It is essentially complete, missing only auth/error context that annotations would normally supply.

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 0%, so the description must compensate and largely does: it documents message_id's source (channel event or get_message_ids), emoji format with a concrete example and the empty-string removal case, and 'to' as the chat alias with default omission behavior.

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 (react to a message with an emoji) and clarifies the dual add/remove semantics. It is clearly distinct from siblings like reply, send_typing, or mark_read, though it does not name an alternative outright.

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?

Implied usage is clear — react to an existing message id — and the note that an empty emoji removes your reaction is a useful usage rule. However there is no explicit when-to-use versus alternatives (e.g. reply), nor any stated prerequisite that a subscription/target must exist.

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