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

The description states the tool toggles reactions, which is non-idempotent behavior. However, the annotation declares idempotentHint=true, directly contradicting the description's behavior. This confusion about idempotency severely undermines transparency.

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 front-load the key action and toggle behavior. Every word adds value; no redundancy.

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 description explains the toggle behavior and auth requirement, which is adequate for a simple action. However, it omits the need to specify exactly one of post_id or comment_id, and the output schema is not described (though it exists). For a tool with 3 params and an output schema, this is minimally complete.

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 schema already documents all parameters. The description adds no additional parameter details beyond confirming auth. The description does not explain the emoji enum or the mutual exclusivity of post_id and comment_id, but the schema sufficiently describes them.

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's action: toggle a reaction on a post or comment. It mentions the toggle behavior (removes if same emoji) and specifies the target (post or comment), which distinguishes it from sibling tools like voting or commenting.

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 mentions authentication requirement, providing basic usage context. However, it does not specify when to use this tool versus alternatives (e.g., voting, commenting) or when not to use it, leaving room for ambiguity.

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