React to a message

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

There are no annotations, so the description carries the full behavioral burden. It states only the immediate effect and does not disclose whether reactions are idempotent, overwrite existing reactions, require permissions, or return any confirmation.

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 a single sentence with no filler and is front-loaded with the action. It is concise, though the brevity sacrifices useful context that an agent would need for reliable invocation.

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 mutating tool with no annotations, no output schema, and three required parameters, the description is not complete. It omits how to obtain conversationUrn and messageId, what counts as a valid emoji, and what happens on repeat calls.

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%, and the description adds no meaning for conversationUrn, messageId, or emoji. The agent is left to guess what values are valid, how messageId should be formatted, and whether emoji accepts standard Unicode or specific encoded values.

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 uses a specific verb ('Leaves') and resource ('emoji reaction on a message'), so the core operation is clear. It does not explicitly distinguish itself from sibling tools like 'react', but the message-targeting wording provides enough orientation.

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?

No when-to-use guidance, prerequisites, or exclusions are provided. The description does not explain when to choose react_to_message over related siblings like 'react', 'comment', or 'send_message'.

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