react_message

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

The description discloses that the reaction is visible to the conversation and that only one reaction can be added per call, which are non-obvious behavioral traits. No annotations exist to supplement, so the description carries the full burden well.

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 efficient sentence followed by a list of reaction types. Every part is relevant and front-loaded, with no redundancy or wasted words.

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?

Given no output schema, the description should cover return behavior or error conditions, but it does not. It adequately explains the action and parameters but lacks complete context for an AI agent to fully predict invocation outcomes.

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. The description adds the reaction type mapping and default value, which mostly repeats schema info. It provides minimal additional meaning beyond the structured 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 clearly states the tool adds a reaction to a LINE message, with specific verb and resource. However, it does not explicitly differentiate from the sibling tool 'cancel_reaction', which is its natural counterpart.

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 guidance is provided on when to use this tool versus alternatives like 'cancel_reaction' or other messaging tools. The description focuses on the reaction types but does not specify prerequisites or when not to use it.

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