react

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

No annotations are provided, so the description carries the full behavioral burden. It discloses two modes (add/remove), which is useful, but does not state required permissions, whether removal requires an existing reaction, or any other side effects or constraints.

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, front-loaded sentence with no filler. It clearly presents the primary action before the alternative remove mode, and every word contributes to the tool's purpose.

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 performs a mutation, has no annotations, no parameters, and no output schema. The description does not explain how to specify the target message or emoji, whether authentication is required, or what happens on success or failure, leaving major gaps for correct invocation.

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?

The schema has 0 parameters, so the baseline is 4. The description mentions a message and an emoji as conceptual inputs, which adds some semantic context, though those inputs are not represented in the schema.

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 specific verb and resource: reacting to a message with an emoji or removing the reaction. It is clearer than a vague operation, but it does not distinguish this tool from the sibling 'reactions' tool, leaving some ambiguity about which one to use for retrieving reactions.

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 no when-to-use guidance, prerequisites, or alternatives. It does not mention when to choose 'react' instead of 'reactions', 'send', or other messaging tools. Usage is left entirely to inference.

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