react_message

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

No annotations provided, so description carries burden. Lists reactionType values and default, and mentions visibility. However, does not disclose side effects, permissions, or rate limits. Adequate but not comprehensive.

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?

Two concise sentences: first for purpose, second for parameter enum. Front-loaded and no unnecessary 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?

Simple tool (2 params, no output schema). Description covers basic purpose and parameters but lacks usage context, return value (fire-and-forget?), or edge cases. Adequate for minimal viability.

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%. Description adds value for messageId by noting it is 'as returned by get_chat_messages', providing context beyond the schema. However, reactionType info largely duplicates 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?

Description clearly states the action: 'Adds a reaction to a LINE message, visible to the conversation.' Specific verb (adds) and resource (reaction to LINE message). Distinguishes from sibling 'cancel_reaction' (which removes reactions) and other messaging tools.

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 explicit guidance on when to use this tool vs alternatives (e.g., cancel_reaction, unsend_message). Only mentions 'One reaction per call' but does not clarify use cases or prerequisites.

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